The book that changes your mind does not know which sentence did it.

Influence works without a receipt. Something rearranged you while you were reading, but the change was cumulative, made of rhythm and accumulation and where you happened to be in your life that month, so no single line can be credited with it. The book has no idea what it did, and often neither do you.

This takes the pressure off looking for the one insight that will change everything. Keep exposing yourself to good work and good people and let the effect be untraceable. And when you make things for others, accept that you will rarely know which part mattered, which is a reason to do the whole of it carefully.