Nature is something that leads me to feel spiritual at times. And... I never thought I'd say this but... Math. And logic, too. A beautifully constructed and compelling argument. Some that I find the most inspiring are attempts to prove the existence of God. Not because I think they are sound at the end of the day, but because I find their form quite beautiful.

David Lewis is someone who I find quite inspiring. Here is a reconstruction:
P1) It is possible that I never came to PsychCentral (thought to be obviously true)
P2) There is a possible world in which I never came to PsychCentral (thought to be a restatement of the obvious truth in P1)
P3) There is a possible world (logically entailed by P2)
Conclusion: Possible worlds exist! (Logically entailed by P3).

Possible worlds exist! I find that an inspiring thought. Whether or not the argument is sound I find it beautiful in its simplicity and in the power and weight and significance that I find in the conclusion. At the moment... I'm feeling spiritual about Dennett's account of the 'library of mendel' and his account of biological possibility with respect to their being a library of all the biologically possible genotypes where that library would consist in more books than there are particles of matter (according to Hawking's estimate).

Helps me feel a sense of wonder and awe.