I read somewhere that projective geometry was an inspiration to Einstein to build the theory of relativity. However, the keyword "projective geometry" isn't mentioned in history of general relativity and only passingly in history of special relativity that Clifford had contributions to the field.

Though the connection has been showed later by Penrose (1984), did it really inspire Einstein? If yes, how?

I read somewhere that projective geometry was an inspiration to Einstein to build the theory of relativity. However, the keyword "projective geometry" isn't mentioned in history of general relativity and only passingly in history of special relativity that Clifford had contributions to the field.

Though the connection has been showed later by Penrose (1984), did it really inspire Einstein? If yes, how? If no, then what really intuitively inspired him?