Thinking

All there is to thinking
is seeing something noticeable
which makes you see something you weren’t noticing
which makes you see something that isn’t even visible.

Norman Maclean in A River Runs Through It, quoted by Frederick Goodman in Algebra – Abstract and Concrete, Ed 2.6, SemiSimple Press

I can’t praise enough Goodman’s book which you can find here, in case you’re interested in (introductory pure) mathematics.

Now, since

faith is the evidence of things not seen

excerpt from Hebrews 11:1 KJV

we can conclude that all there is to thinking is the knowledge of faith.