wow what a great thread! i have languished far too long in cash and stt poker threads and what a pleasure as a philosophy and english graduate to dip my toes here tentatively and slightly vaguely
On the philsophy side I find understanding the classic Greek philsophers essential to how we think of Philosophy today and the philosophical problems they discussed were the most complex and fundamental I learned
Plato - The Republic, Theaetetus, Sophist, The Theory of Forms and Socratic Dialogues
Aristotle - from various sources and largely inferred so as such not readable in a few books
On the history side I loved Herodotus, the 'Father of History' - The Nines Muses in particular
As general sages I loved writers such as Shakespeare and Charles Dickens who teach us so much about humanity and society via the medium of beautiful writing and story telling
As a pig ignorant maths and physics man I found works on chaos and quantum theory like
The quantum theory of superposition by Erwin Schrödinger in 1935 and later laymans interpretations of it fascinating
All takes me back to studying Ancient History and Philsophy as school and university respectively - great memories!