Charles H. Spurgeon on Psalms 77:6

Diligent search. Thus duty requires diligence. External acts of religion are facile; to lift up the eye to heaven, to bow the knee, to read a prayer, this requires no more labour than for a papist to tell over his beads; but to examine a man's self, to take the heart all in pieces as a watch, and see what is defective, this is not easy. Reflective acts are hardest. The eye can see everything but itself. It is easy to spy the faults of others, but hard to find out our own. Thomas Watson.