A similar question is here, in which a comma is used in place of a conjunction like and.
I came across the following quotation of C. S. Lewis which reads,
“What you see and what you hear depends a great deal on where you are standing. It also depends on what sort of person you are.”
Assuming the website which quoted Lewis did not misquote him, should Lewis have used the plural verb, depend? Or is there some arcane rule of grammar of which I am unaware which allows for a plural subject and a singular verb?