Consider first, that the passions of love and desire, when they are unmortified, branch out into all manner of vices and vicious inclinations commonly ranged under the seven heads, which are usually called the Seven Capital Sins - though St. John reduces them all into these three, "the lust of the flesh, the lust of the eyes, and the pride of life" (1 John 2). Now, amongst these vicious inclinations which wage war against the soul there is usually some one or other that is stronger and more violent than the rest, or that occasions more or greater sins, and this is named by divines the predominant passion, the mortification of which is one of the chief businesses of a spiritual life. For this predominant passion being, as it were, the captain and commander of the rest, when this is overthrown, the rest will more easily be subdued and brought under, as when their champion Goliath was slain the Philistines were all immediately put to flight.

This predominant passion, has already unhappily gained the heart, it is but too apt to impose upon the poor soul with specious pretexts, in order to keep its hold, and to maintain its ground against the voice of conscience and all the calls and graces of Heaven. This predominant passion, which has taken possession of your heart, is indeed the capital enemy of God and your soul; it must be slain, it must be sacrificed to the living God. Beware of the traitor which you carry about with you; suffer him not to impose upon you; if you have not a mind to be wilfully blind, to discover what he would be at; because upon the least examination of your hearts you will find him always busy in undermining the reign of the love of God, thrusting himself upon His throne, and setting up an idol in His temple, by challenging the main place in your heart to the prejudice of divine love.