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.
Love of God proceeds from conversing with him; this conversation of prayer comes about through stillness, and stillness comes with the stripping away of the self.
The love of God is not something we learn from another. Neither did we learn from another how to love the sunshine or how to defend our life. Nor has anyone taught us how to love our parents, or those who have reared us. And so, indeed much more, learning how to love God does not come to us from outside. But in the very commencement of the life of man, there is placed within us a certain seminal conception, having, from itself, the beginnings of a natural propensity towards this love.
The soul that really loves God and Christ, though it may do ten thousand righteousnesses, esteems itself as having wrought nothing, by reason of its insatiable aspiration after God. Though it should exhaust the body with fastings, with watchings, its attitude towards the virtues is as if it had not even begun to labor for them.
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.
True joy is the joy of consolation, the joy that wells up in the knowledge of one's own weakness and the Lord's mercy, and that does not need the bared teeth of laughter to express itself.