Thomas A Kempis 1.13 (part 2) - Schooled by life

The beginning of temptation is instability of the soul, and a lack of confidence in God. Like a ship without a rudder is driven by the waves, so a man who is unmoored from his purpose is carried along by various temptations. As fire tests iron, so temptation tests the upright man. Often we do not know what strength we have; but temptation reveals what we are. Carefully watch the beginnings of temptation, when it's easiest to defeat the enemy, if the door of the mind is closed to him, when he is confronted as soon as he has knocked. As someone said, 

Stop the problem at the gate,
Harder to cure the longer you wait.

The first thing that comes to the mind is a simple suggestion, then the strong imagination, afterwards pleasure, evil affection, and assent. And slowly the enemy enters completely, since he was not resisted from the start. And however much a man delays resisting, every day he makes himself weaker, and the enemy against him stronger. 

Some suffer the worst temptations in the beginning of their conversion, some at the end, and some for nearly their whole life. Some are tempted lightly, according to the divine decree of wisdom and justice, who weighs the state and merit of man, and orders all things for the wellbeing of his chosen ones. 

So we should not lose hope when we are tempted, but earnestly ask God, who is worthy, to help us in all our troubles; that he will, as St. Paul says, with the temptation he provides a way that we can bear it. Let's humble ourselves then under the hand of God in all temptation and trouble, for the humble in spirit he will save and lift up. 

In temptations and troubles a man is tested as to what progress he has made, and in those temptations his greater merit shows, his strength and virtue is clearer. It is no great thing if a man is devoted and faithful when he has no deep struggles; but if he can bear patiently in times of adversity, then is there great hope. Some are guarded from great temptations, but are often defeated in everyday life so that they are humbled, never trusting themselves in great things, as they are weak in small things.

Imitation of Christ by Thomas A Kempis, 1.13 (second part). 

Translation focused on contemporary English and preservation of rhetorical force and art