The young man knows the ...

The young man knows the rules, but the old man knows the exceptions.
The young man knows the rules, but the old man knows the exceptions.
 Oliver Wendell Holmes Jr.

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

We do not quit playing because we grow old, we grow old because we quit playing.
 Oliver Wendell Holmes Jr.
It is the province of knowledge to speak, and it is the privilege of wisdom to listen.
 Oliver Wendell Holmes Jr.
What lies behind us and what lies before us are small matters compared to what lies within us.
 Oliver Wendell Holmes Jr.
Fame usually comes to those who are thinking about something else.
 Oliver Wendell Holmes Jr.
A man may fulfil the object of his existence by asking a question he cannot answer and attempting a task he cannot achieve.
 Oliver Wendell Holmes Jr.