The letters collected at the end of the volume may be looked on as short essays of a somewhat informal character. The apology for reprinting them is this, that whereas in a regular essay the writer assumes his own standpoint, and may be suspected of ignoring the vantage-ground of his opponents, in replying to a correspondent he must, at least to some extent, follow the lead of an antagonist, and fight, if he fights at all, on the field which another has chosen. As I cannot reprint the various able compositions which I have attempted to answer, it will be fair, to one at least of the writers, to remark that I have personal reason to know that he still retains the opinions of which I attempted to disabuse him. He contrives to reconcile this obduracy to his own intelligence by laying stress on the candid admission made by Darwinians, that the Theory of Development is for the present that which they call it,--a Theory, and not a demonstration. No one pretends to answer fully every objection that has been urged against the Theory. The evidence is as yet incomplete. By its very nature it must perhaps always to some extent remain so. The proof depends in part upon analogy, which leads to conclusions possible or probable, rather than to what is demonstrably certain. But the advocates of the Theory, remembering Bishop Butler’s maxim, that ‘to us probability is the very guide of life,’ endeavour to maintain that their opinions have far more than that minimum of preponderance which, in Butler’s view, not only justifies, but imperiously exacts, the adhesion of reasonable beings. THOMAS R. R. STEBBING. Torquay, Feb. 6, 1871. CONTENTS. PAGE DARWINISM[1] 3 THE NOACHIAN FLOOD[1] 34 INSTINCT AND REASON[2] 62 HUMAN NATURE AND BRUTE NATURE 82 THE LAPSE OF TIME[1] 93 NOTE ON THE HYPOTHESIS OF SPONTANEOUS GENERATION[1] 126 IMPERFECTION OF THE GEOLOGICAL RECORD[1] 133 DARWINISM: THE NOACHIAN FLOOD 147 DARWINISM: SCIENCE AND RELIGION 152 DARWINISM, AND THE FIRST VERTEBRATE 156 THE FIRST VERTEBRATE, AND THE BEGINNING OF REASON 160 OYSTERS OF THE CHALK, AND THE THEORY OF DEVELOPMENT 165 THE MATHEMATICAL TEST OF NATURAL SELECTION 168 THE GENESIS OF SPECIES 173 INDEX 181 NOTES to pp. 13 and 34.