“The gentlest of us will know that the tigers of wrath are to be preferred to the horses of instruction and will consider it intellectual cowardice to take into account what happens to those who ride tigers.”

Introduction
The allusion to the "tigers of wrath" and "horses of instruction" is from William Blake's The Marriage of Heaven and Hell: Proverbs of Hell
The Portable Matthew Arnold (Viking Press, 1949)
Context: Disgust is expressed by violence, and it is to be noted of our intellectual temper that violence is a quality which is felt to have a peculiarly intellectual sanction. Our preference, even as articulated by those who are most mild in their persons, is increasingly for the absolute and extreme, of which we feel violence to be the true sign. The gentlest of us will know that the tigers of wrath are to be preferred to the horses of instruction and will consider it intellectual cowardice to take into account what happens to those who ride tigers.