PSALM 4:8 I will both lay me down in peace, and sleep:

I have hitherto considered wherein true religion doth consist, and how desirable a thing it is; but when one sees how infinitely distant the common   temper and frame of men is from it, he may perhaps be ready to despond, and give over, and think it utterly impossible to be attained. He may sit down in sadness, and bemoan himself, and say, in the anguish and bitterness of his spirit, “They are happy indeed whose souls are awakened unto the divine life, who are thus renewed in the spirit of their minds; but, alas! I am quite of another constitution, and am not able to effect so mighty a change. If outward observances could have done the business, I might have hoped to acquit myself by diligence and care; but since nothing but a new nature can serve the turn, what am I able to do? I could bestow all my goods in oblations to God, or alms to the poor, but cannot command that love and charity, without which this expense would profit me nothing. This gift of God cannot be purchased with money. If a man should give all the substance of his house for love, it would utterly be contemned. I could pine and macerate my body, and undergo many hardships and troubles; but I cannot get all my corruptions starved, nor my affections wholly weaned from earthly things. There are still some worldly desires lurking in my heart, and those vanities that I have shut out of the doors, are always getting in by the windows. I am many times convinced of my own meanness, of the weakness of my body, and the far greater weakness of my soul; but this doth rather beget indignation and discontent, than true humility in my spirit. And though I should come to think meanly of myself, yet I cannot endure that others should think so too. In a word, when I reflect on my highest and most specious attainments, I have reason to suspect,  that they are all but the effects of nature, the issues of self-love acting under several disguises; and this principle is so powerful, and so deeply rooted in me, that I can never hope to be delivered from the dominion of it. I may toss and turn as a door on the hinges, but can never get clear off, or be quite unhinged of self, which is still the centre of all my motions; so that all the advantage I can draw from the discovery of religion, is but to see, at a huge distance, that felicity which I am not able to reach; like a man in a shipwreck, who discerns the land, and envies the happiness of those who are there, but thinks it impossible for himself to get ashore.”