While we've youth in our hearts, we can never grow old.

On every stem, on every leaf,... and at the root of everything that grew, was a professional specialist in the shape of grub, caterpillar, aphis, or other expert, whose business it was to devour that particular part.

Beware of making your moral staple consist of the negative virtues.

I think that we should be eternally vigilant against attempts to check the expression of opinions that we loathe and believe to be fraught with death, unless they so imminently threaten immediate interference with the lawful and pressing purposes of the law that an immediate check is required to save the country.

Knowledge and timber shouldn't be much used till they are seasoned.

We have been cocksure of many things that were not so.

To be civilized is to be potentially master of all possible ideas, and that means that one has got beyond being shocked, although one preserves one's own moral aesthetic preferences.