If someone is judged worthy to receive the gift of knowledge but allows his heart to be full of bitterness or rancor or aversion to another, it is as if he had been struck in the eye by a thornbush. That is why knowledge is no good without charity.
Walk before God in simplicity, and not in subtleties of the mind. Simplicity brings faith; but subtle and intricate speculations bring conceit; and conceit brings withdrawal from God.
Let all of us who wish to attract the Lord to ourselves draw near to Him as disciples to the Master, simply, without hypocrisy, without duplicity or guile, not out of idle curiosity. He Himself is simple and not composite, and He wants souls that come to Him to be simple and guileless. For you will surely never see simplicity bereft of humility.
May simplicity go before you everywhere; especially be simple in your faith, hope, and love, for God is an Essence of Simplicity, a Unity that is worshipped everlastingly, and our soul is simple. The simplicity of our soul is hindered by our flesh, when we please it.
Those who meditate unceasingly upon the holy and glorious name [of Jesus] in the depths of their heart can sometimes see the radiance of their own spirit-intelligence. For when the mind is profoundly concentrated on this invocation, we feel experientially how it starts burning off all the layers of dirt that normally suffocates the soul.
If you have received from God the gift of knowledge, however limited, beware of neglecting charity and temperance. They are virtues which radically purify the soul from passions and so open the way of knowledge continually.
You are, I am sure, aware that for you penitence is now no longer limited to disclosing your sins to your confessor, but that you must now bear your sins in mind always, until your heart nearly breaks with their ugly load; and would break, were it not for your firm faith in the mercy of our Lord.