The Art of War- expressed better than any other piece I've read the rationale of war. War is conflict and understanding both the enemy and yourself is the only way to effective success.
Atomic Habits- the best way to improve your life is to improve the minutia of it by just 1%. Applies rationale to how we operate while on auto pilot and gives effective solutions to combat the negative habits we fall into.
The Way of Monkey Book- an amazing, modern lens to stoicism and individually written in the style of eastern texts. While the author is deplorable to say the least, the message and morals of the work brilliantly reflect the ebb and flow of nature and the distortion of such through the actions of the average man.