Anything whose presence or ...

Anything whose presence or absence makes no discernible difference is no essential part of the whole.
Anything whose presence or absence makes no discernible difference is no essential part of the whole.

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.