It does not pay a man to exist until the age of Methuselah by making his days indolent and useless. The more this is reflected upon, the more the ref… - Frederick II of Prussia

[A] man with all the algebra in the world is often only an ass when he knows nothing else. Perhaps in ten years society may derive advantage from the curves which these visionary algebraists will have laboriously squared. I congratulate posterity beforehand. But to tell you the truth I see nothing but a scientific extravagance in all these calculations. That which is neither useful nor agreeable is worthless. And as for useful things, they have all been discovered; and to those which are agreeable, I hope that good taste will not admit algebra among them.

Hero demolished both his friends and his soldiers, who had helped him in the execution of his plans; he found new friends, and raised other troops. I say, in spite of Machiavel and of the ingrates, that this policy of Hero is very bad, and that it is much more prudent to trust the troops which have tested and known value, and have friends whose loyalty has also been tested. The new and unknown ones are also unsafe. I leave the reader to push this reasoning further; all those who detest ingratitude, and who truly value friendship, will not remain neutral on this matter.

My people and I," he said, "have come to an agreement which satisfies us both. They are to say what they please, and I am to do what I please.