The thing that jumps out to me is how well read Einstein is, some of the modern day scientists could do with a much broader education. CP Snow's two cultures argument seems more relevant now than ever.
I think the philosopher who had the most influence on Einstein (and on other physicists of the early 20th century) was Arthur Schopenhauer:
> Schopenhauer was well read by physicists, most notably Einstein, Schrödinger, Wolfgang Pauli, and Majorana. Einstein described Schopenhauer's thoughts as a "continual consolation" and called him a genius. In his Berlin study three figures hung on the wall: Faraday, Maxwell, Schopenhauer. Konrad Wachsmann recalled: "He often sat with one of the well-worn Schopenhauer volumes, and as he sat there, he seemed so pleased, as if he were engaged with a serene and cheerful work."
> When Erwin Schrödinger discovered Schopenhauer ("the greatest savant of the West") he considered switching his study of physics to philosophy. He maintained the idealistic views during the rest of his life. Wolfgang Pauli accepted the main tenet of Schopenhauer's metaphysics, that the thing-in-itself is will.
From what I understand, Einstein’s education and cultural milieu was very influenced by Kant, but Einstein himself was personally more interested in Schopenhauer.
To quote Schopenhauer (English translation):
```
But space and time are not only, each for itself, presupposed by matter, but a union of the two constitutes its essence, for this, as we have seen, consists in action, i.e., in causation
```
That's the kind of thinking that could help Einstein formulate an idea of "spacetime"
