and (5) inference; also, but in a subordinate degree, (6) testimony, and (7) common sense. By our harmonious use of these motives we may, I think, attain rational certainty, and secure a sound foundation on which we may securely raise a complete philosophical edifice.

F. I shall be disposed to agree with you if in our next discussion you can dispose of my idealistic objections-my scepticism, that is, as to our real knowledge of the external world as anything external to us and independent of our existence. You see, in order to

M. What is the matter, Frankland? Why, you tremble like an aspen—are you ill?

F. My dear fellow, there is Emily and her mother -those ladies in black at the door of the Burlington Hotel! Let us turn and go home at once. Till I have seen my guardian again I could not bear to meet them.

M. Cheer up, Frankland; you will make it right with him yet. I feel sure that it will all end well. She is fond enough of you, you know, to be willing to wait even if he holds out, but I cannot think he will allow a mere social prejudice to spoil your happiness.

F. He is such a worldly old man, that I think an angel whose father had been in business would never do for him.

M. That is a new conception of angelic nature! But, how you did start!

F. Don't say anything about it, Maxwell! I am ashamed of being so weak, but I confess that the mere thought of her under present circumstances so

upsets me that sometimes, for the moment, I quite forget where I am and what I am doing.

M. Well, it is a long time since breakfast, and you have had no lunch, but a long philosophical talk instead. Let us go home and drop metaphysics in favour of things about which no one is practically sceptical.

According to the foregoing argument we have a direct knowledge of our own being in action-our own self-activity. From this, by a reflex act, we may have absolutely certain knowledge either of the existence of our own state of mind-our present feeling-or of the existence of our own substantial self. We may become as clearly and certainly aware of one of these as of the other, and of the existence of either (self or state) in the past, as well as in the present. It being manifest that everything cannot be proved, it has been pointed out that all proof must ultimately rest on what is self-evident, to believe which is the very reverse of believing blindly. Absolute scepticism is not only irrational, but selfcontradictory, and our memory may suffice to convince us that we do know objective truth, as for example our own past, and not merely appearances. Intellect, it has been urged, and not sense, is the ultimate judge of truth, and some things are seen to be certainly true not by a mere negative impotence, but actively and positively. Thus here again, as also in memory, the mind is carried by its own force from subjectivity to objectivity, and it sees that certain things are not only subjectively but also objectively evident, and the presence of such complete or 'simple'

evidence—that is evidence both objective and subjective is the supreme test of truth. That we should know the self-evidence of things is wonderful, but not more wonderful than is every kind of knowledge. It is plain that if we would reason or even think coherently, we must accept the practical adequacy of speech to convey thought and the validity of inferences logically made. We must also admit the value of overwhelming human testimony, and the respect due to the common-sense judgments of mankind in ordinary practical matters. Altogether, if what has been contended is correct, it seems possible to formulate, with confidence, the following propositions :

1. There is such a thing as certainty, both with respect to the past and to the present.

2. All knowledge must ultimately rest upon truths which are self-evident.

3. Such truths may be both objectively and subjectively evident.

4. The intellect, and not sense, is the ultimate test of truth.

5. There is one supreme criterion of truth—simple evidence.

6. There are various distinct motives or grounds of certainty.

7. These are: consciousness, the senses, memory, intellectual intuition, inference, testimony, and com

mon sense.

8. Nothing less than the combined use of the whole of these suffices for philosophical knowledge. 9. It is only by the harmonious employment of all these means that a true philosophy can be attained.

CHAPTER III.

THE OUTER WORLD.

LINCOLN'S INN FIELDS.

Can we have a certain knowledge of an external world existing independently of ourselves such as physical science postulates ? NATURAL Science offers an inexhaustible field for the activity of man's powers of observation, comparison, and reasoning. A first-class modern museum, such as that which owes its origin to the genius of John Hunter, is very wonderful when we reflect how little even the best instructed amongst us are able to gather from its contents, compared with the as yet unrecognised treasures of knowledge which are therein enshrined, and lie awaiting future observation.

Two days later than that of the conversation at Eastbourne, the two friends had been together examining the contents of that admirable collection.

Maxwell. What a different place this museum is now from what I recollect it five-and-twenty years ago! Then visitors were rare enough. Now, a man has to choose his time very carefully if he wants to have it pretty well to himself.

Frankland. Oh! All the world and his wife come here now that such a number of 'at homes have been held in this place. The skeletons have

a lively time of it. I have seen more than one flirtation carried on under the friendly shelter of the megatherium, and have known a man made happy for life between the jaws of the 'right' whale!

M. But biological science has really made a wonderful advance in the last twenty years, and a real love for it has become widely diffused.

F. True enough! But still more diffused is the pretence of having a love for it! It has become 'the thing' to be scientific and to rush after any lecturer

in vogue. But real, downright, sincere interest in science is still far too rare. Of the many who visit the Botanical Gardens how very few take the trouble to leave the promenade in order to examine any object of scientific interest of which they see a notice at the gate which the secretary has been careful to put up!

M. No doubt fashion has much to do with it, and people like to trifle with it as they like to flirt a little with philosophy-under the guise of 'agnosticism,' as they call it. I only wish, if they do take to the latter, they could be got to go into it deeply. But it is quite the exception for anyone to be willing to pursue the subject, even as closely as you did at Eastbourne. When shall we examine together the question as to the external world'?

F. Now, if you like! I think we have done our survey of that part of it which forms this collection.

M. What have you to say, then, against my certainty as to the real existence, independently of my own mind, of all these bones and bottles about us?

F. Before replying I will ask you a preliminary question. You will admit that we often have prolonged, consistent, and vivid dreams; that as long as