From Suicide pg 163:
Reflection only develops when it becomes necessary for it to develop; that is to say, if a certain number of unconsidered ideas and feelings which, until then, had sufficed to govern behaviour, have become ineffectual. At such times, reflection intervenes to fill the void that has been created–but which has not been made by it. Just as it fades to the extent that thought and action take on the form of automatic habits, so it only emerges as and when established habits are falling apart.
Mark Carrigan 