A man of knowledge lives by ...

A man of knowledge lives by acting, not by thinking about acting.
A man of knowledge lives by acting, not by thinking about acting.

More phrases

If one does not know to which port one is sailing, no wind is favorable.
What a distressing contrast there is between the radiant intelligence of the child and the feeble mentality of the average adult.
We are masters of the unsaid words, but slaves of those we let slip out.
I have always found that mercy bears richer fruits than strict justice.
A lie gets halfway around the world before the truth has a chance to get its pants on.

Quotes from the same author

The trick is in what one emphasizes. We either make ourselves miserable, or we make ourselves happy. The amount of work is the same.
“We choose whether to be warriors or to be ordinary.”
“A warrior seeks to act rather than talk.”
“A warrior lives by acting, not by thinking about acting, nor by thinking about what he will think he has finished acting.”
“A warrior never worries about his fear.”