"The most unpractical merit of ancient piety became the most practical merit of modern investigation."

Our actual obligations to Matthew Arnold are almost beyond expression. His very faults reformed us. The chief of his services may perhaps be stated thus, that he discovered (for the modern English) the purely intellectual importance of humility. He had none of that hot humility which is the fascination of saints and good men. But he had a cold humility which he had discovered to be a mere essential of the intelligence. To see things clearly, he said, you must "get yourself out of the way." The weakness of pride lies after all in this; that oneself is a window. It can be a coloured window, if you will; but the more thickly you lay on the colours the less of a window it will be. The two things to be done with a window are to wash it and then forget it. So the truly pious have always said the two things to do personally are to cleanse and to forget oneself...

This humility, as I say, was with Arnold a mental need. He was not naturally a humble man; he might even be called a supercilious one. But he was driven to preaching humility merely as a thing to clear the head. He found the virtue which was just then being flung in the mire as fit only for nuns and slaves: and he saw that it was essential to philosophers. The most unpractical merit of ancient piety became the most practical merit of modern investigation. I repeat, he did not understand that headlong and happy humility which belongs to the more beautiful souls of the simpler ages. He did not appreciate the force (nor perhaps the humour) of St. Francis of Assisi when he called his own body "my brother the donkey." That is to say, he did not realise a certain feeling deep in all mystics in the face of the dual destiny. He did not realise their feeling (full both of fear and laughter) that the body is an animal and a very comic animal. Matthew Arnold could never have felt any part of himself to be purely comic— not even his singular whiskers. He would never, like Father Juniper, have "played see-saw to abase himself." In a word, he had little sympathy with the old ecstasies of self-effacement. But for this very reason it is all the more important that his main work was an attempt to preach some kind of self-effacement even to his own self-assertive age. He realised that the saints had even understated the case for humility. They had always said that without humility we should never see the better world to come. He realised that without humility we could not even see this world.

-Excerpt from Chesterton's Introduction to Essays Literary and Criticial by Matthew Arnold (1906)