And what does really matter? ...

And what does really matter? That is easy: thinking and doing, doing and thinking--and these are the sum of all wisdom. . . . Both must move ever onward in life, to and fro, like breathing in and breathing out.
And what does really matter? That is easy: thinking and doing, doing and thinking--and these are the sum of all wisdom. . . . Both must move ever onward in life, to and fro, like breathing in and breathing out.

Quotes from the same author

Knowing is not enough; we must apply. Willing is not enough; we must do.
Just trust yourself, then you will know how to live.
The really unhappy person is the one who leaves undone what they can do, and starts doing what they don't understand; no wonder they come to grief.
What is not started today is never finished tomorrow.
A man sees in the world what he carries in his heart.