We report [the following] on the authority of a letter of Joseph Purdew, an observer, equally exact and judicious. “This morning,” he says, “while reading in bed, I was suddenly interrupted by a noise similar to that made by rats, when running through a double wainscot, and endeavouring to pierce it. The noise ceased for some moments and then recommenced. I was only at two feet from the wainscot, and I observed it attentively: a great rat made its appearance at the mouth of a hole; it looked about, without making any noise, and having reconnoitered as much as it wished, it retired. An instant after, I saw it come again, leading by the ear another rat, larger than itself, and which appeared aged. Having left this at the edge of the hole, it was joined by another young rat. The two overrun the chamber, collecting the crums of biscuit which, at supper the preceding evening, had fallen from table, and carried them to the rat which they had left at the edge of the hole. I was astonished at this attention on the part of the animals. I continued to observe with care. I perceived that the animal to which the two others brought food was blind, and unable, except by feeling about, to find the biscuit they offered. I no longer doubted that the two younger ones were its offspring, the assiduous and faithful purveyors of a blind parent. I admired within myself the wisdom of Nature, who has given to all animals a social tenderness, a gratitude, I had almost said a virtue, proportionate to their faculties. From that moment, these abhorred vermin seemed to become my friends. They gave me, for my conduct in a similar case, lessons which I have not often received from mankind. At this juncture, a person opened the door; the two young rats warned the blind one by a cry; and, in spite of their fright, would not seek for safety till that was secure; they followed as the latter withdrew, and, so to say, served him for a rear-guard.”

—J. & B. Williams, publishers: The Wonders of the Universe: Curiosities of Nature and Art, Including Memoirs and Anecdotes of Wonderful and Eccentric Characters of Every Age and Nation from the Earliest Period to the Present Time (1836)