All knowledge which is unfelt and inoperative puffs up the mind and hardens the heart.
We must not perceive only, but we must feel; and feeling, of course we experience.
The head may be strengthened till the heart is starved. A gracious experience arises from operations and influences which are spiritual, from an inward principle which is divine, a communication of God, a participation of the divine nature: Christ living in the heart, the Holy Spirit dwelling there in union with the faculties of the soul as an internal vital principle, exerting his own proper nature in the exercise of those faculties. Now it is no wonder that that which is divine is powerful and effectual, for it has omnipotence on its side.