"A man may lack the feeling of his faith, and cry and call again and again for it, and feel nothing all the while, and yet nevertheless have true and sound faith; for the feeling of and mourning for the lack of faith, and the earnest and constant desire of it, is an infallible sign of faith. 

  A spark of fire is only little, yet it is fire as well as the whole element of fire; and a drop of water is but little, yet it is water as well as the whole ocean. If there is only one grape on a vine, it shows that it is a vine, and that the vine is not dead; so put the case that there is only but the appearance of a little grace in a Christian, perhaps the Spirit of God appears but in one grace in him at that time, yet that one grace shows that we are vines, and not thistles, thorns or base plants, and it shows that there is life in the root." 

Thomas Brooks.