Perhaps related, I've read that Al-Khwarizmi's book on algebra [0] contained no equations or even any numerals. It was apparently a wall of text.

My take is that you pretty much had to be a philosopher to make your way through a text like that. Al-Khwarizmi wrote down a general solution to the quadratic equation, which had eluded humanity since the ancient Greeks. Today, the solution and its proof are taught to schoolchildren.

One thing that's happened is that notation has been improved. For instance we now have equations and we use numerals to write numbers.

Similar deal with Newton and Leibnitz. The notation that we use for teaching calculus resembles theirs but has been improved. Perhaps moreso for Newton's mechanics. Philosophers debated about Newton, now we teach his ideas to schoolchildren.

Likewise Clerk Maxwell. What I've read is that his theory was also unreadable by most of us, but his successor, Heaviside, came up with the notation that we teach to slightly older schoolchildren.

This seems to be a recurring story. Maybe someday there will be a notation that makes string theory seem obvious... to schoolchildren. ;-)

[0] The origin of both words "algorithm" and "algebra"

> I've read that Al-Khwarizmi's book on algebra [0] contained no equations or even any numerals

Yes the use of symbols came much later. Algebra used to be couched in terms of do this to that quantity while maintaining that relation between that and that quantity then to the quantity obtained in that step ....