whatever value its conclusions may have, will prove useful to some readers by putting them in a position to appreciate the extraordinarily interesting and fruitful discoveries of biology in recent years. “The lotus of physics,” as Schopenhauer says, “is rooted in the soil of metaphysics,” and if these studies pretended to offer a complete explanation of the riddle of existence, the metaphysical basis for the speculations contained in them would have to be elaborated at considerable length. But, after all, the conclusions reached would only be those which most people are willing to accept as a necessary assumption, if all thought on the constitution of the universe is not to be a pure futility. Suffice it to say Man is here regarded as an organic part of Nature, and his consciousness as Nature’s way of mirroring herself to herself. Since, like other natural things, the soul is not a complete and unalterable entity, but is part of the eternal Becoming, it never can be claimed that its reflection of the world is absolutely pure and complete, yet some reality, some significance this reflection must surely have. The fact that man is not something different from the world, observing it from outside, but is vitally related to it, would alone entitle us to believe that, however much his observations may need to be purified and corrected, and however false may be the argumentative deductions sometimes drawn from them, he is still capable of a real and fruitful apprehension of the phenomena by which he is surrounded, and of their relations to each other and to himself. All sincere thought must therefore tend to brighten a little the mirror of the human soul. If this book should do so in any degree, were it merely by provoking other minds to more successful labours, the writer will thankfully say, like Apollo’s temple-sweeper in the play of Euripides, Fair is the service of Light. T. W. ROLLESTON. Glenealy, Co. Wicklow. _I have to thank The Macmillan Co. for permission to reproduce two illustrations (Figs. 1 and 2) from Wilson’s_ The Cell in Development and Inheritance, _and Mr. Edward Arnold for a similar favour in regard to Fig. 3 from Weismann’s_ The Evolution Theory. CONTENTS PART I. BIOLOGY CHAPTER I The Argument from Design PAGE Paley and the Watch 1 The Analogy Inapplicable 4 Paley’s Conception of Design 8 The Evolutionary Conception 11 Conquest of Nature by the Evolution Theory 16 The Philosophic Basis of Nature-study 17 CHAPTER II The Wheel of Life Continuity of Animal, Vegetable, and Mineral Life 21 Characters of Organic Life 23