"It is a curious phenomenon that there never was a religion started in this world with more antagonism…(to the worship of forms) than Mohammedanism…The Mohammedans can have neither painting nor sculpture, nor music…That would lead to formalism. The priest never faces his audience. If he did, they would make a distinction. This way there us none. And yet it was not two centuries after the Prophet’s death before saint worship (developed). Here is the toe of the saint! There is the skin of the saint! So it goes, Formal worship is one of the stages we have to pass through."
January 1, 1970
https://en.wikiquote.org/wiki/Aniconism_in_Islam