We ought not to desire the impossible.

Let not things, because they are common, enjoy for that the less share of our consideration.

... we
do not admire what
we cannot understand.

We desire nothing so much as what we ought not to have.

In any case, we do not advance the human cause by refusing to consider ideas that make us frightened.

We mistrust anything that too strongly challenges our ideal of mediocrity.

Let us beware of common folk, common sense, sentiment, inspiration, and the obvious.

What cannot be imagined cannot even be talked about.

We have so much difficulty imagining nothingness.

We must never make experiments to confirm our ideas, but simply to control them.

469. — We never desire earnestly what we desire in reason.

That, what we cannot describe mathematically cannot have a recognizable existence.

The things we counterfeit are not worth the trouble of falling into disgrace with ourselves.

Never will this prevail, that the things that are not are — bar your thought from this road of inquiry.