Quote from Lucius Annaeus Seneca,
"You are doing an excellent thing, one which will be wholesome for you, if, as you write me, you are persisting in your effort to attain sound understanding; it is foolish to pray for this when you can acquire it from yourself. We do not need to uplift our hands towards heaven, or to beg the keeper of a temple to let us approach his idol's ear, as if in this way our prayers were more likely to be heard. A god is near you, with you, and in you. This is what I mean, Lucilius: there sits a holy spirit within us, one who marks our good and bad deeds, and is our a guardian."
Lucius Annaeus Seneca (more quotes by Lucius Annaeus Seneca or books by/about Lucius Annaeus Seneca)
(4 B.C.-A.D. 65) Roman Stoic philosopher, statesman, dramatist, "Seneca the Younger"
Epistulae Morales ad Lucilium (Moral Letters to Lucilius), Letter XLI: On the god within us
Persistence, Understanding, Folly, Prayer, Independence, Idolatry, God, Security