Truth is like a vast tree which yields more and more fruit the more you nurture it. The deeper the search in the mind of truth, the richer the discovery of the gems buried there.
Do not yield to Satan's enticements; rather, stand firm for truth. The unsatisfied yearnings of the soul will not be met by a never-ending quest for joy amidst the thrills of sensation and vice. Vice never leads to virtue. Hate never promotes love. Cowardice never gives courage. Doubt never inspires faith.
The only way to get rid of a temptation is to yield to it. Resist it, and your soul grows sick with longing for the things it has forbidden to itself, with desire for what its monstrous laws have made monstrous and unlawful.
How do you measure whether or not a strategy of economic growth that is articulated by a very smart, capable economist actually yields growth? You can't. But you can influence.
Poets and men of action differ: the former yield to their feelings in order to reproduce them in lively colors, and therefore judge only ex post facto; the latter feel and judge at one and the same time.
However we select from nature a complex [of phenomena] using the criterion of simplicity, in no case will its theoretical treatment turn out to be forever appropriate (sufficient).... I do not doubt that the day will come when [general relativity], too, will have to yield to another one, for reasons which at present we do not yet surmise. I believe that this process of deepening theory has no limits.