It is the mark of an educated ...

It is the mark of an educated mind to expect that amount of exactness which the nature of the particular subject admits. It is equally unreasonable to accept merely probable conclusions from a mathematician and to demand strict demonstration from an orator.
It is the mark of an educated mind to expect that amount of exactness which the nature of the particular subject admits. It is equally unreasonable to accept merely probable conclusions from a mathematician and to demand strict demonstration from an orator.

Quotes from the same author

It is the mark of an educated mind to be able to entertain a thought without accepting it.
Change in all things is sweet.
Well begun is half done.
In all things of nature there is something of the marvelous.
Happiness depends upon ourselves.