This is a quote by Newton. Grammatically, “diverting myself” modifies “a boy,” so it should be “himself,” right?
I don’t know what I may appear to the world, but to myself I seem to have been only like a boy playing on the seashore, and diverting myself in now and then finding a smoother pebble or a prettier shell than ordinary, whilst the great ocean of truth lay all undiscovered before me.
nicetomeetyouso it should be “himself,” right?
No. The reflexive pronoun refers to the subject.
Newton is writing in first person. He is not describing someone else (a boy) that he knows. He is describing himself as a child.