Some of the happiest evenings of younger days were spent in the rooms of university students. It was pleasant to be near persons who dwelt in the kingdom of knowledge, who could wander at will on the mountain tops of science and literature, and have glimpses of unknown lands of light which I might never see. Who has seen London under the reign of the sun, after a sullen, fitful season, knows how wondrous is the transformation. Like the sheen of the gods the glittering rays descend, dispelling and absorbing the sombre clouds. A radiance rests on turret and roof. Then hidden creatures that crawl or fly come forth and put on golden tints. The cheerless poor emerge from their fireless chambers with the grateful emotions of sun worshippers. How like is all this to the change which comes over the realm of ignorance! Light does not change vegetation more than the light of knowledge changes the realm of the mind. The thirsty crevices of thought drink in, as it were, the refreshing beams. Once conscious of the liberty and power which comes of knowing--ignorance itself becomes eager, impatient--covetous of information. Faculties unsuspected disclose themselves. Qualities undreamed-of appear. So it came to be my choice to enter the field of instruction. It seemed to me a great thing to endow any, however few, in any way, however humble, with the cheeriness and strength of ideas. True, I began to teach what I did not know--or knew but partially--yet not without personal advantage, since no one knows anything well until he has tried to teach it to another. The dullest pupil will make his master sensible of defects in his own explanation. Formerly, the dulness of a learner was supposed to discover the necessity of a cane, whereas all it proved was incapacity or unwillingness to take trouble--on the part of the teacher. The result was that I wrote several elementary books of instruction. All owed their existence, or whatever success attended them, to the experience of the class-room. All things have an end, as many observant people know, and before long I turned my attention to journalism. I had read somewhere a saying of Aristotle--"Now I mean to speak conformably to the truth." That seems every man's duty--if he speaks at all. Anyhow, Aristotle's words appeared to constitute a good rule for a journalist I had never heard or never heeded the injunction of Byron:-- "Let him who speaks beware Of whom, of what, and when, and where."