We have an instinctive association of white with goodness and purity, and black with evil. Some scientists believe that our conception of blackness may be associated with the fundamental and ancient fear of dirt and contagion.

Two University of Virginia psychologists attempted to explore this phenomenon in a laboratory. How strong is the association between white/goodness and black/evil? To test this association they used an adapted Stroop test. The standard Stroop test consists of printing names of colors in ink of a contrasting color—say, the word “yellow” in blue ink. Participants are then asked to state the color of the ink, rather than reading the word. Subjects often get confused and read the word itself rather than stating the color. Our minds are used to interpreting the written word and less used to paying attention to the color of the ink.

Using a similar principle, the University of Virginia psychologists flashed words with moral value—such as “greed” or “honesty”—on a screen, in either black or white ink. Subjects tended to read the “moral” words faster when they were printed in white ink, and the “immoral” words faster when they were printed in black ink. They seemed to have an innate association of immorality with blackness and purity with white.

In the Torah, too, we find a strong association of the color white with purity and holiness. In the Holy Temple, the high priest wore white garments on Yom Kippur. Similarly, a red string was tied around the horn of the Se’ir l’Azazel, the scapegoat thrown down a mountaintop as part of the Yom Kippur service. If the string turned white, that was a symbol that the repentance of the Jews had been forgiven.

A well-known verse in Isaiah (1:18) states, “If your sins prove to be like crimson, they will become white as snow; if they prove to be as red as crimson dye, they shall become as wool.” On its surface, this verse seems redundant—what is the difference between “white as snow” and “as wool”? Commentaries explain that there is a difference in purity between fresh snow and wool. Wool, even after it is washed, still retains some slight impurity. here is a level of teshuvah (return) that will render our sins “like snow”—meaning that no remnant of the sin will remain at all. If we perform a lower level of teshuvah, though, the sin will be “like wool”—purified to some extent, but not completely.

As part of the process of Redemption, as the prophet Daniel says (12:10), “They will be clarified and whitened, and many will be purified.” Our sins will be removed completely, leaving no remnant whatsoever, like pure white snow.