There was a time when coloring matter was not used in the making of cheese. Consequently, chalk and cheese were of the same whiteness. Such, at least, was the state of affairs in the fourteenth century . . . [when] comparisons of chalk with cheese began to crop up at every opportunity. . . . Such comparisons carry on to the present time from habit, though for several centuries the two substances no longer have had even a superficial resemblance.

—Charles Earle Funk, from Heavens to Betsy! and Other Curious Sayings, 1955.