“The heart is deceitful above all things, and desperately sick;
who can understand it?” – Jeremiah 17:9 (ESV)
That the heart of every man naturally is full of deceit and guile, and therefore desperately wicked. Solomon spoke of four things hard to be found out, the going of a ship on the sea, a snake upon the rock, etc (Proverbs 30:19), because these leave no steps to trace them by; but you see an harder thing than all these to find out. The heart of a man, and that not only in respect of others, others cannot know what is in a man’s heart; but of our own selves, we are not able to dive into those depths: there is an abyss, a deep within every man’s heart, whereby he knows not the bottom of his ways: Who thinks not but that he repents, he believes, he loves God, when his heart deceives him all the while: So that as this is a large subject to preach upon, so it’s a very profitable and necessary point. Indeed this is the beginning of our conversion, when a man comes to be undeceived: Till his deceitfulness of the heart be in part removed, there is a great gulf between you and true repentance.
~ Anthony Burgess, A Treatise of Sin: The Deceitfulness of the Heart Unmasked
Abide in Christ 