Bach’s two books of The Well-Tempered Clavier, composed in the first half of the 18th century, have been of inestimable influence. Even a cursory study of the works reveals the profundity of the artistry.
For example, Timothy Smith begins his comments on the 24th fugue in b minor, in the first book, with the following:

The Well-Tempered Clavier, Book I, Fugue 24 in B minor, subject (Courtesy: Timothy Smith)
“This subject uses all twelve pitches of the chromatic scale…. It is notable that the most chromatic of subjects in the 48 is reserved for the key of B minor. The convergence of chromaticism with key is not an accident of the cycle’s alphabetical order…. Bach associated this key with Christ’s passion… It should not surprise us therefore that the B minor subject contains three crosses. This mannered metaphor was stock in trade for sacred music of the period. Also called chiasmus from the Greek letter Chi (χ), the motive was associated with two ideas: Christ and his cross (with χ being the first letter in the Greek spelling of Christ, and graphically in the form of a cross)…. [E]very four quavers of the ‘sigh’ motif [form] the cross shape.”
And this is only the beginning. The meanings, and the literature exploring them, are vast.
Yet the works were not written for monetary profit. Performers of exceptional mastery, such as Pablo Casals and András Schiff, convinced of Bach’s paramount position in western music, start their day of work with the study of Bach’s music. In Casals’s instance, after a walk along the ocean, he studied two of the preludes and fugues of the The Well-Tempered Clavier. Schiff spends an hour at the piano. It seemed purposeful to endeavour to replicate, insofar as possible, this type of practice for my own artistic work.
The Casalsian Pacific, at English Bay, Vancouver. 19 April 2016. (Photo: Hendrik Slegtenhorst)
I am fortunate to live very near the Pacific Ocean. The poem “’Cello on Comox Street,” the sixth publication from Constellations of Desire, a work in progress, has been published in Triadæ, accompanied by an image created by the author, and its translation into Spanish by Spanish poet Eva Gallud. The subject of the poem is the interrelationship of art and nature, and includes exemplifications of Johann Sebastian Bach’s The Well-Tempered Clavier and Catalan cellist Pablo Casals. Gallud and I have collaborated on four previous publications. Material from this work has also appeared in Dalhousie Review, published by Dalhousie University in Halifax, Nova Scotia.
The work cited is at pages 16-17.