When a spirit has reached the end of the term assigned by Providence to his errant life, he chooses for himself the trials which he determines to undergo in order to hasten his progress - that is to say, the kind of existence which he believes will be most likely to furnish him with the means of advancing and the trials of this new existence always correspond to the faults which he has to expiate. If he triumphs in this new struggle, he rises in grade; if he succumbs, he has to try again.

p. 202. - The Spirits' Book