Blog 42: 2.1.9 - 2.2.3
The 'total' in Total Depravity means that 'the whole man is overwhelmed - as by a deluge - from head to foot, so that no part is immune from sin and all that proceeds from him is to be imputed to sin' (2.1.9). The sin that is ours from the beginning of our existence invades and pervades every aspect of our being.
That is not to say that sin is any part of the definition of our humanness. We dare not, Calvin says, search out God's handiwork in our own pollution (2.1.10). In a state of nature, that is, in our fallen condition, our nature is deranged and degenerate. The wound was not there from the beginning. It was inflicted, but it was inflicted by our own sin. Man, consequently, is 'corrupted through natural vitiation, but a vitiation that did not flow from nature' (2.1.11).
This distinction is necessary to maintain the true meaning of, for example, Ephesians 2:3 - 'we are all by nature children of wrath'. This does not mean that the nature with which our Maker endowed us at the outset was objectionable to Himself, or that our sin is some flaw in His design. But it does mean that sin is now our natural condition, and it exists through no fault but our own.
Calvin will illustrate the totalness of this corruption with reference to man's freedom of choice. Care is needed to explore the issue lest, on the one hand, we provide an excuse for ourselves in emphasising our lack of power, and, on the other hand, rob God of his glory by crediting ourselves with too much. We have nothing to boast of - the poverty of our fallen condition ought to leave us seeking the glory of the God whose grace alone is equal to our need.