[This essay was delivered as an evening address on August 24, the Monday of the Association week.  A vast stir had been created by the treatment of deep-reaching problems in Professor Tyndall’s presidential address; interest was still further excited by this unexpected excursion into metaphysics.  “I remember,” writes Sir M. Foster, “having a talk with him about the lecture before he gave it.  I think I went to his lodgings—­and he sketched out what he was going to say.  The question was whether, in view of the Tyndall row, it was wise in him to take the line he had marked out.  In the end I remember his saying,] ‘Grasp your nettle, that is what I have got to do.’” [But apart from the subject, the manner of the address struck the audience as a wonderful tour de force.  The man who at first disliked public speaking, and always expected to break down on the platform, now, without note or reference of any kind, discoursed for an hour and a half upon a complex and difficult subject, in the very words which he had thought out and afterwards published.

This would have been a remarkable achievement if he had planned to do so and had learned up his speech; but the fact was that he was compelled to speak offhand on the spur of the moment.  He describes the situation in a letter of February 6, 1894, to Professor Ray Lankester:—­]

I knew that I was treading on very dangerous ground, so I wrote out uncommonly full and careful notes, and had them in my hand when I stepped on to the platform.

Then I suddenly became aware of the bigness of the audience, and the conviction came upon me that, if I looked at my notes, not one half would hear me.  It was a bad ten seconds, but I made my election and turned the notes face downwards on the desk.

To this day, I do not exactly know how the thing managed to roll itself out; but it did, as you say, for the best part of an hour and a half.

There’s a story pour vous encourager if you are ever in a like fix.

[He writes home on August 20:—­]

Johnny’s address went off exceedingly well last night.  There was a mighty gathering in the Ulster Hall, and he delivered his speech very well.  The meeting promises to be a good one, as there are over 1800 members already, and I daresay they will mount up to 2000 before the end.  The Hookers’ arrangements [i.e. for the members of the x club and their wives to club together at Belfast] all went to smash as I rather expected they would, but I have a very good clean lodging well outside the town where I can be quiet if I like, and on the whole I think that is better, as I shall be able to work up my lectures in peace...

August 21.