"These words which I command you this day shall be upon your heart; and you shall teach them diligently to your children, and shall talk of them when you sit in your house, and when you walk by the way, and when you lie down, and when you rise. And you shall bind them as a sign upon your hand, and they shall be as frontlets between your eyes. And you shall write them on the doorposts of your house and on your gates."
"It would indeed be strange that the Jews should have the law written in a book hanging from their hands so that they might always remember the commandments, and we did not impress indelibly in our memory the words of a faith which is so much higher. Owing to the fact that immediately after having received the Divine order Adam met the Demon and was easily overcome by him because of his lack of meditation and contemplation of that order, it is imperative that in all this time you should continually meditate on the words of the Creed so that it may be strengthened in you and deeply fixed in your mind, and so that you may love your religion without which you cannot receive the Divine gift, or if you receive it, you cannot keep it and hold fast to it."
--Theodore of Mopsuestia, Liber ad Baptizandos II.II