Really recommend the book which Sertillages mentions-and is parallel with-that is: “Les Sources (wellsprings)” by Alphonse Gratry. If you want a more “theoretical” take on the matter, and have an even more open mind toward Gratry-who is perhaps even more of a true believer than Sertillanges. The translated English version even has a list of similar books in the preface regarding intellectual self-culture. Payot’s Education of the Will is similar. Ernest Dimnet’s Art of Thinking is also similar. Dinmet has something of a personality, haha. Gratry is pretty extreme and has densely-beautiful sentences. Payot is on the practical side of things, mainly the attitude of seizing transitory emotional states and using or changing them for your benefit, and maintaining focused, not scatterbrained, study.

Table of Contents of Gratry’s Wellsprings: >Counsels for guidance of mind Silence, morning work Inspiration Evening, rest Prayer Reading Specific advice for: [Faith: comparative science Math,astronomy, physics, physiology, geography, geology, history, ethics, theology] >counsels for conduct of life Aphorisms of science of duty Science of duty Duties of man toward himself Duties of man towards others, family Conclusión

And again, these books can be skimmed and jumped around through with the tables of contents-don’t have to brute-force. Just gather the honey of that severe attitude towards Truth, towards plowing crosswise all disciplines and being careful with not reading too much words, but thinking deeply and clearly