Edged tools are dangerous things to handle, and not infrequently do much hurt.
— Agnes Repplier

I know how many days in which I have just answered e-mail, had three phone calls and a two hour lunch. Poof, gone. They are not infrequent.
Joseph Epstein infrequency quote

There is a constant in the average American imagination and taste, for which the past must be preserved and celebrated in full-scale authentic copy; a philosophy of immortality as duplication. It dominates the relation with the self, with the past, not infrequently with the present, always with History and, even, with the European tradition.
— Umberto Eco

First impressions are often the truest, as we find (not infrequently) to our cost, when we have been wheedled out of them by plausible professions or studied actions. A man's look is the work of years; it is stamped on his countenance by the events of his whole life, nay, more, by the hand of nature, and it is not to be got rid of easily.
— William Hazlitt

Thought is a process of exaggeration. The refusal to exaggerate is not infrequently an alibi for the disinclination to think or praise.
— infrequency quotation by Eric Hoffer