On the Origin of Species by Charles Darwin; reading to induce cosmic-existential dread, I tend to see the book similar to the monolith in '2001: A Space Odyssey', something that really shakes at the core of humanity's frontier in the face of ever expanding knowledge.
I was looking through a box of my old books lately and I found this! I was looking through it recently, some of it is definitely pretty interesting.
I've always admired him as a historical figure. He just seemed like a brilliant scientist, someone who understood life on a profound level and basically revolutionized the study of human origins (a topic I'm interested in and enjoy reading about), and also just generally a good person...supposedly he was a loving husband & devoted father. He married his cousin, and that's kind of weird from my modern perspective, but hey. To me he's like a Newton or Oppenheimer type character, someone who had a rare and gifted mind.
One claim Darwin made that still blows me away is that we evolved into human beings in Africa. To us this seems obvious but in Darwin's time it would've been extremely controversial...the oldest human remains found during Darwin's century ("Java Man") were found in southeast Asia, for example, and (iirc) Alfred Russel Wallace (the co-founder of evolutionary theory) speculated that we had evolved there, not Africa. Africa then was viewed by many Europeans as just a backwater to exploit, whereas today we know that it's the most genetically-diverse continent on the planet and basically the incubation chamber for our entire species, and what was a very controversial and incendiary claim then is just considered as fact now