People habituate themselves ...

People habituate themselves to let things pass through their minds, as one may speak, rather than to think of them. Thus by use they become satisfied merely with seeing what is said, without going any further. Review and attention, and even forming a judgment, becomes fatigue; and to lay anything before them that requires it, is putting them quite out of their way.
 Joseph Butler

Quotes from the same author

The satisfaction that accompanies good acts is itself not the motivation of the act; satisfaction is not the motive, but only the consequence.
 Joseph Butler
Virtue is not to be considered in the light of mere innocence, or abstaining from harm; but as the exertion of our faculties in doing good.
 Joseph Butler
As this world was not intended to be a state of any great satisfaction or high enjoyment, so neither was it intended to be a mere scene of unhappiness and sorrow.
 Joseph Butler
Happiness or satisfaction consists only in the enjoyment of those objects which are by nature suited to our several particular appetites, passions, and affections.
 Joseph Butler
Things and actions are what they are, and the consequences of them will be what they will be: why then should we desire to be deceived?
 Joseph Butler