No man is able to make ...

No man is able to make progress when he is wavering between opposite things.
No man is able to make progress when he is wavering between opposite things.

Quotes from the same author

Men are disturbed not by things, but by the view which they take of them.
It is the nature of the wise to resist pleasures, but the foolish to be a slave to them.
Keep silence for the most part, and speak only when you must, and then briefly.
Know, first, who you are, and then adorn yourself accordingly.
We have two ears and one mouth so that we can listen twice as much as we speak.