The "essays" actually came into existence as programme notes written by Tovey to accompany concerts given (mostly under his own baton) by the Reid Orchestra in Edinburgh. Between 1935 and 1939 they were published in six volumes as Essays in Musical Analysis. Each volume focused on a certain genre of orchestral or choral music (for example, Volumes I and II were devoted to 'Symphonies'; Volume III to 'Concertos'), with perhaps two or three dozen works discussed with the help of plentiful music examples. In 1944 a posthumous seventh volume appeared on chamber music.
As befits their origin in introductory notes for the concert-going public, Tovey's Essays are unforbidding and occasionally even light-hearted in tone. His fondness for "Humpty Dumptyish" language may irritate at times, but overall Tovey's achievement is impressive: very few commentators have been able to communicate clearly with a non-specialist readership at the same time as revealing so much that is of interest to the trained musician and musicologist. (Readers who wish to see Tovey at his most densely technical may care to examine his book A Companion to Beethoven's Pianoforte Sonatas and its bar-to-bar analytic commentary).
In the Essays Tovey saw his role as being "counsel for the defence" (Introduction to Volume I): in speaking up on behalf of the work about to be performed, he was seeking to facilitate the listener's appreciation of its artistic content and technical merits. As a result, his approach tends to 'track' the structure of a work as it unfolds through time before the ear of his imaginary "naive listener".