Or some Ravi Shankar at the Monterey Pop Festival in 1967:
You name it! But imagine the situation in, say, 1773, when Mozart was seventeen years old and already a mature composer with several operas, over twenty symphonies and enormous amounts of other music under his belt. But he could not go to YouTube and hear what everyone else was doing. And by "everyone else" of course I just mean Joseph Haydn, who by this point had already revolutionized the symphony and written fifty in the new form. What was the new form? Here is what Wikipedia (quoting from an 1895 history of music) says:
The "Italian" style of symphony, often used as overture and entr'acte in opera houses, became a standard three-movement form: a fast movement, a slow movement, and another fast movement. Haydn and Mozart, whose early symphonies were in this form, eventually replaced it with a four-movement form through the addition of a second middle movement (Prout 1895, 249).This sounds like Haydn and Mozart came up with the final four-movement form together, but the truth is that it was Haydn all by himself. The three-part Italian sinfonia was a fairly brief form and apart from the first couple of symphonies by Haydn, written in the late 1750s for his first employer, Count Morzin, he quickly settled on a four-movement form for the next one hundred and some symphonies. Everyone else came to it later and much more tentatively, including Mozart who was writing symphonies very much in the older form as late as 1779 with the Symphony No. 32, K. 318:
The whole piece is under ten minutes in length and the third "movement" is a continuation of the first, labelled: "tempo primo". This is a remarkably primitive kind of symphony to be writing in 1779 when Haydn had already written seventy symphonies in the new style: four movements, with a minuet and trio and lasting around twenty minutes or more. And as late as 1776, C. P. E Bach was also still following the three movement fast-slow-fast model with a duration of around ten minutes.
Now Mozart did, with exposure to the symphonies of Haydn, get with the program, but the great majority of his symphonies written before 1780, and even some after like No. 34, K. 338, are written in the three movement form and are light, frothy or exuberant diversions even if of a longer duration:
Just a few of the early Mozart symphonies are in the four-movement Haydn model, but they really stand out. Take the Symphony No. 25, K. 183, known as the "Little G minor":
As Wikipedia notes:
With its wide-leap melodic lines and syncopation, this symphony is characteristic of the Sturm und Drang style. It shares certain features with other Sturm und Drang symphonies of this time, and is likely inspired by Joseph Haydn's Symphony No. 39 which is likewise in G minor.Another of the early symphonies that really stands out is No. 29, K. 201 with an opening theme that you will never get out of your head:
In some areas, such as the concerto and opera, Mozart had nothing to learn from Haydn, but when it comes to the symphony, the influence is clear and flows only one way. Why was Haydn such a decisive force in the genre of the symphony? Apart from his sheer genius, I suspect that it was because for his entire career, first with Count Morzin, then with the Esterházy family, he had at his complete disposal, every day, a symphony orchestra. In the early days a small one of fewer than 20 players, but even so, it was still an orchestra. I can think of few if any other composers who had this advantage--certainly not Mozart whose career was very much pillar to post.
When I decided to start writing symphonies, my instinct was to listen to all the important composers of symphonies: Haydn, Mozart, Beethoven, Schumann, Brahms, Dvorak, Mahler, Bruckner, Sibelius and so on. Haydn had no need to do that because, apart from people like C. P. E Bach (who wrote his first symphony in 1741 and nearly forty years later was following roughly the same three-movement form) there WAS no-one writing symphonies. Haydn was the ball-game. And Mozart only gradually came to know Haydn's music. A similar instance is that of J. S. Bach, who, as a young man, got to know the music of Vivaldi by copying it out laboriously by hand in candlelight.
When people today talk about how classical music is "inaccessible" I just have to laugh! Nowadays it is ALL accessible.
Here, for your further information, are lists of all the symphonies of Haydn and Mozart. Links to individual works are clickable.