The term "early music" sometimes causes confusion. As a very casual indication, music from the 1400s is early music in the sense which we use here, whereas music from the 1940s is not. The context is European classical music, which had its best-known pieces written in the 1700s & 1800s, and so the "early" in early music means earlier than that. In this way, early music usually designates the Medieval, Renaissance, and Baroque periods of Western music. Early Music is a standard term, used in trade magazines, journals, record store classical sections, etc.
Precise date-based definitions of the stylistic periods of Western music, and by implication of "early music" in sum, are a rather illusory goal. The most common ending date given for the Baroque period is 1750, with the death of J. S. Bach. This is a convenient and acceptable date, frequently used in definitions of early music, but it is also a simplification of the various stylistic events of the period. If one views the Baroque as a style with specific traits, then those traits were being overturned in favor of those of the "Classical" style by some composers before this date, and persisted in the work of some other composers after this date. Stylistic periods are designated only later, by historians who necessarily prioritize certain features over others.
Baroque music has its origins in the rise of the recitative style among Monteverdi and others, the beginning of opera as a form, and the consequent adoption of basso continuo. In fact, the end of the Renaissance style around 1600 is among the clearest divisions in Western music, owing to the simultaneity of these changes, as well as to the self-conscious way in which Monteverdi and others advocated them. The beginning of the Renaissance is less clear. There are two major changes to be considered, the use of the interval of a third as a stable harmony and the new humanistic orientation to text with music at its service. In this case, the important changes occurred over several decades, and so although most references will place the beginning of the Renaissance with the new harmonies of Dufay around 1420, others will place it with the humanistic texts of Josquin around 1500. Some of the former references will then call the latter period the High Renaissance. Some European classifications include only the Medieval & Renaissance periods under the early music label, with the Baroque period considered separately.
Obviously, what we know about music and its performance tends to decrease as we look farther backward in time. This is due to less writing of original sources, to more chance for destruction of sources which were written, and also to the temporal distance between these people and ourselves making it less likely that we will understand statements and instructions in the same way. We hope to overcome the latter factor with study and familiarity, but the former two are inherent barriers. Designating a beginning to Medieval music is one area where knowledge is too vague to give a precise date. Various trends do emerge in the 1100s, such as relatively large volumes of written notated polyphony and non-liturgical Latin song. It is tempting, therefore, to locate the "beginning" of the Medieval music period at this point, especially because of the general historical factors surrounding the "Twelfth Century Renaissance." However, such a designation marginalizes the closely related pre-12th century repertory, and that repertory possesses no clear starting point at all.
The beginning of polyphony, something which likely occurred in improvised form centuries prior to the major codifications of the 1100s, is a central event in Western musical history. However, surviving Medieval musical sources are actually dominated by plainchant. It is a correspondingly large area of study & performance, in various regional & historical styles. Not only were there the semi-mythical consolidations of Gregorian chant, but various earlier chant repertories for which some manuscript sources survive. There are also some scattered sources of ancient music which might broadly be considered under the term early music. Owing to its greater historical distance, this music is rather distinct from the usual "early music" repertories and so is often considered separately, especially as none of it survives from Western Europe itself. There is a true break here, with no discernible stylistic continuity between surviving ancient music and the earliest Western plainchant of centuries later.
It is easy enough to say that early music means music of the Medieval, Renaissance and Baroque periods, but why is it those periods in particular? The answer is relatively simple. Beginning with the late 18th century music of Mozart & Haydn, some works simply never stopped being put before the public. Mozart & Haydn's music, and especially Beethoven's in the following generation, was performed in public concerts during their lifetimes and then after their deaths, continuously to the present day. This is a fairly noticeable change, historically speaking, as earlier music frequently was not performed even a few decades after it was written. There were various exceptions to this basic trend, especially in ceremonial music such as that used in the Vatican or for royal funerals. More broadly, plainchant & tunes in general are a very conspicuous and distinct exception. However, early music becomes early by virtue of not generally having had this public continuity, even if it did have various threads of scholarly or specialized continuity.
To turn a convoluted phrase, early music is etymologically the music which is earlier than the earliest music which was typically being performed in concerts at the time when performers decided to perform early music. For the most part, this happened in the 1900s, gradually over the course of a few decades in the beginning & middle of the century. Some of the first institutions to revive Renaissance music on a larger scale were the English Cathedral Choirs, and they now have a long-standing tradition of performing this music. Their early entry into this repertory was facilitated by various embryonic musicological revival efforts in England in the 1800s and even notably the 1700s, and buoyed by interest in Renaissance music among early 20th century English composers. By the 1950s, early music was a definite phenomenon, with such performers as Safford Cape, Alfred Deller, Noah Greenberg, etc. Since then, the number of early music performers has increased steadily, as has audience interest, to the point where early music sales are more or less equal to those of non-early classical music.
Beyond historical technique, which remained under study with examples from these eras in a fairly continuous way in academia, and with which many prominent composers were associated at one time or another, there were some notable revivals prior to the decisive one which has defined the Early Music Movement as such. Mendelssohn's revival of Bach's St. Matthew Passion in 1829 is probably the single most significant such event, although the survival of Handel's Messiah in re-orchestrations by Mozart and others is also notable, especially as these events conditioned some of the first musical antiquarian societies in England. In this way, some composers' works have performance traditions which predate the present Early Music revival, but which do not generally extend continuously to their actual lifetimes. These various performance threads can be interesting to consider, especially as the Early Music movement itself becomes more extensive in both history and stylistic range. For instance, the history of musical revival in England is quite involved, leading to many ramifications for different performance styles today.
The idea of revival has become a touchstone for the Early Music Movement, and consequently the fact that some styles of performance have been going on long enough to develop and build their own continuity presents some philosophical complications. Early music performers have a history of going directly to written & manuscript sources, and consequently not basing their interpretations so much on what other performers have done, but more on their own direct intuition of the sources themselves. This is very different from what "mainstream" performers have generally done, and so the latter have a history of continuity with and development of previous performance ideas as such. The existence of performance continuity within the early music community itself provides something of a bifurcation in the goals of performers, as to this point early music has been fundamentally a radical movement.
The idea of wanting to perform music only a few decades older than the 18th century music already being performed regularly does not seem very radical. However, the desire to base interpretations directly on original sources, rather than on the way previous performers had interpreted them, has had significant ramifications. For one thing, copying and modifying a previous performance, perhaps extending back in a chain to that of the composer himself, is a rather different skill from intuiting it directly after a lapse of some decades. The necessity of taking this step for chronologically early music has led directly to conflicts with interpretations which are based on performance history, especially such earlier revived performance histories as that for Bach. A battle cry has become "composer's intentions" together with the huge body of philosophical argument which that notion implies, and so there has been a general trend toward "recreating" the sound world from which the composition arose. This act necessarily puts the performer at some distance from the event to be recreated, and so is mediated fundamentally by textual sources.
When Bach's music was revived by Schumann and Mendelssohn, it was performed and even transcribed in 19th century style. Orchestrations were updated, piano parts were added to the Sonatas & Partitas for Solo Violin, etc. It seemed natural to them to perform the music, which they had "discovered" and found valuable, in the style of their own time. As interest increased, and with it curiosity, especially regarding the difficulties involved in performing Bach's keyboard music on the piano, the idea of "original instruments" arose in this repertory. Bach's music simply sounds rather different on a harpsichord than it does on a piano, while the former also enforces different ideas on phrasing, ornament, dynamics, technique, etc. The idea that older sonorities might be interesting on their own terms, and not need updating, was also radical, and created another fundamental impetus for the Early Music Movement. However, the term "original instruments" has been mostly abandoned for two important reasons: There are questions about just how original "original" means when it comes to available reconstructions or surviving specimens, and also "instruments" gives a skewed labeling of historical vocal technique.
Labels such as "authentic performance" and "composer's intentions" have likewise been mostly abandoned, but this time primarily for philosophical rather than practical reasons. There are two basic facts underlining this decision. The first is that knowing precisely how a work was originally performed, especially one rather distant in time, is not really possible. The second is that, perhaps with a few exceptions, composers do not state their intentions with regard to hypothetical performances hundreds of years in the future. The idea that the composer "wants" the music to sound today exactly as it did for the first performance is simply a philosophical one. Judging by their own actions, one might conclude that Schumann and Mendelssohn would have expected or even wanted their music to be "updated" for new stylistic eras. This is partly an issue in the wake of Beethoven, a composer who had some difficulty achieving a performance in practice which fit what he had in mind. One can interpret this fact either as a call to redouble one's efforts to achieve precisely what he had in mind, or more generally to develop performance ideas in such a way as to make the once impossible rendition possible. Which exactly is the intent? For Bach's Mass in b, which was never performed in his lifetime? For music of even earlier composers, who probably did not anticipate it being heard ten years after their deaths?
One basic fact seems inescapable: Learning more about the circumstances surrounding the creation of a piece of music leads to a greater understanding of it. The sonorities and resources of historical voices & instruments give insight into phrasing & articulation. Historical tuning gives insight into harmonic motion. Especially in the case of music very distant from us, such as Medieval or early Renaissance music, some "common sense" ideas on how music should be performed, as based on typical practice today, are very different from those described in historical treatises. Although ultimately a performer makes an artistic decision as to what and how to perform today, understanding these differences can lead to a more informed decision, even if modern instruments or other factors are eventually chosen. This is what makes the term "Historically Informed Performance" (or HIP) fairly widely accepted today.
In its own time, the setting for early music was very different from today, and so e.g. performing Medieval music in a concert hall is already inherently an anachronism. Facts such as this are unavoidable, even if performers painstakingly research and interpret music according to historical sources. Likewise, the mere idea of "historical performance" is primarily a modern one, and so attempting to render works in this way contains some philosophical contradictions which cannot be resolved. With the right attitude, these philosophical pitfalls are simply a way to ensure that musical performance will remain a creative activity. One can even extend the context in all directions, from using period-style instruments and vocal technique, to placing the music into its historical social context in a historical building in historical costume. Such extremes are less common, but can also be fun, provided one remembers that there is nothing one can do to recreate a historical audience, i.e. an audience for which the music is truly new.
What then is an authentic performance? This is an emotionally charged question, at least when asked concerning repertories with competing performance traditions. Although the label "historically informed performance" seems fairly neutral and seductive, in the sense that one can hardly vilify gaining information, there are also strong implications regarding how informed one must be and how that information must be used. As more information becomes available, and as the movement progresses on its own terms, various practical questions arise in addition to the more theoretical ones about the nature of text & composition. It is one step to decide to perform Bach's music on harpsichord rather than on piano, but as alluded to in the dismissal of the "original instruments" term, there are continuing questions of precision regarding which harpsichord. This is only the beginning, because at least hypothetically, every nuance of the physical performance can be exactly as it was for Bach. If one values information concerning historical context, and wants to use as much as one can as faithfully as possible, there is still a point at which one simply must stop studying and start performing. Otherwise, there is no performance and no music.
To return to a fundamental issue, even the hypothetical perfect reproduction of the original performance presents theoretical problems. At some level of precision, and for relatively early music this level is not very fine at all, the notation and available sources will not dictate every detail. Phrasing, nuance, the most delicate inflections of single notes... these are not included in notation. The performers must make these decisions, especially as they reflect their own physical gifts or inclinations. Singers will not sound identical, even if their technique is the same. This is part of what makes music a living art, something which must be continually reinterpreted in order to exist (until the invention of recordings). More than that, the composition of a piece, especially one which we would want to hear centuries later, was a creative act made in the context of creative musicians. In this sense, if musicians today are to abandon any creativity when rendering old music, then they are not authentic, because that is not the frame of mind under which the original was made. The same frame of mind is indeed impossible today, because the piece will never be new again. Of course, for many individuals, it will seem new, and that is part of what has made the revival aspect of early music so successful and exciting.
Performance histories have frequently reflected ideas such as "progress" & "evolution" and consequently an underlying implication that scoring & interpretation should be updated to reflect contemporary concerns & possibilities. There have been normative judgements at work. However, there have also been inherent contradictions, as the continuing performance of works by Mozart & Beethoven clearly suggests that the classical music community has not viewed more recent compositions as simply better. Throughout Western musical history, there have been statements that the new music of the time was self-evidently superior to that of the previous generation, but these statements have become increasingly fringe judgements since the era of Beethoven. It is not by coincidence that the early music movement traces some of its deepest roots to the following generations. Once one begins to believe that some earlier music is no worse, or perhaps even better, than what is being written now, the idea that even earlier music and performance practices are worthwhile too cannot be far behind.
In some ways, nothing has changed. Performance histories continue to reflect contemporary concerns & possibilities, even if these differ substantially from what they once were. The growing desire today for a musical museum reflects various factors in society, not least of which is a multicultural awareness that the art of other times & places can speak to us. It may also reflect some disturbing psychological facts of contemporary life, but such a discussion would move rather far from the topic here. Beyond any of this, a fundamental understanding of historical changes in style and artistry leads naturally to an expansion of our ideas on what music must be. This is something which early music gives to contemporary music-making as a whole, something which may prove enormously productive as early music moves firmly into the popular consciousness of the 21st century.
Early music is therefore either music which is chronologically early (as in "before 1750"), or an attitude toward performance which can be applied to any music (as in "Historically Informed Performance"). Frequently it is both, canonically so. For more specific examples and discussion, please examine other sections of the FAQ.
Practitioners of early music tend to have rather different ideas on precisely how these factors work out and delineate themselves in practice. The question remains somewhat open, which is a big reason that the topic always produces interesting discussion on our forum. That early music cannot fully define itself also ensures it will remain a living art.