When first even the least drop of faith is instilled in our minds, we begin to contemplate God’s face, peaceful and calm and gracious towards us. We see him afar off, but so clearly as to know we are not at all deceived. Then, the more we advance as we ought continually to advance, with steady progress, as it were, the nearer and thus surer sight of him we obtain; and by the very continuance he is made even more familiar to us.
So we see that the mind, illumined by the knowledge of God, is at first weapped up in much ignorance which is gradually dispelled. Yet, by being ignorant of certain things, or by rather obscurely discerning what it does discern, the mind is not hindered from enjoying a clear knowldge of the divine will toward itself. For what it discerns comprises the first and principal parts in faith. It is like a man who, shut up in a prison into which the sun’s rays shine obliquely and half obscured through a rather narrow window, is indeed deprived of the full sight of the sun. Yet his eyes dwell on its steadfast brightness, and he receives its benefits .
Thus, bound with fetters of an earthly body, however much we are shadower on every side with great darkness, we are neevertheless illumined as much as need be for firm assurance when, to show forth his mercy, the light of God sheds even a little of its radiance.
– John Calvin, The Institutes of the Christian Religion