I made a comparison at table some time since, which has often been quoted, and received many compliments. It was that of the mind of a bigot to the pupil of the eye; the more light you pour on it, the more it contracts.

Oliver Wendell Holmes, Sr. (1809-1894) American poet, essayist, scholar

“The Autocrat of the Breakfast Table,” Atlantic Monthly (1858-04)
    (Source)

Often trimmed/paraphrased to "The mind of a bigot is like the pupil of the eye; the more light you pour upon it, the more it will contract." Frequently misattributed to his son, Oliver Wendell Holmes, Jr.

The Autocrat himself correctly comments that a similar phrase appears in Thomas Moore, Preface to the poems "Corruption" and "Intolerance":

The minds of some of our statesmen, like the pupil of the human eye, contract themselves the more the stronger light there is shed upon them.

The Autocrat goes on to note, "When a person of fair character for literary honesty uses an image such as another has employed before him, the presumption is, that he has struck upon it independently, or unconsciously recalled it, supposing it his own."

Collected in The Autocrat of the Breakfast Table, ch. 6 (1858)