vi INTRODUCTION. 



any difference ? The agency in the latter case is invisible, because it 

 is an internal force, a something acting inside the material. It is as 

 though the visible shipwright were away, and his art were inherent in 

 the timber itself. It is the case of a physician getting well, not that 

 of a physician curing another person. Moreover, if the agency itself 

 be out of sight, the model from which it works is visible enough ; is 

 as visible and palpable as the model of the ship or the plan of the house, 

 and, like them, examinable before either is constructed. For the germ 

 jor seed will not develop after any chance pattern,^ but will grow in the 

 Ukeg^ess of its parent. Nature's model is that parent form. The seed 

 of an olive will not produce any chance plant, but an olive like that 

 /from which it came. Man gives rise to man, and horse to horse. The 

 doctrine of Empedocles ignores this fact.^ You say, or Empedocles 

 said, that the multiform interaction of the countless combinations of 

 matter gives rise to every conceivable form of being ; but that those 

 forms alone survive that have the necessary conditions of survival.'^ Be 

 it so. But the olive and the man are not the only beings that have 

 these conditions. Why, then, do they always produce offspring like 

 themselves ? * Why not any one of the other countless possible forms 

 of life ? Clearly because there is something else than the chance 

 combinations of necessary properties of matter, guiding and directing 

 these to a preconcerted end. This something else is what I call Nature. 

 I grant that, as Nature is invisible, her existence is an hypothesis, but 

 her works are visible and the hypothesis is founded upon the contem- 

 plation of these.' If you ask me whether this hidden force acts, as 

 the builder or the shipwright, with conscious deliberation, and conscious 

 adaptation of means to ends, I do not know. Even art is not always 

 deliberative." The highest art goes straight to its end without delibera- 

 tion. So, too, the swallow builds its nest and the spider its web without 

 deliberation, and yet each in nicest adaptation to its wants.'' Why may 

 Thot Nature be a similar force implanted in matter, undeliberating though 

 \guiding to a rational end } All I assert is, that there is something 

 at work in living bodies more than the common necessary properties 

 of inanimate matter, something which, whether deliberative or not, 

 acts as would an intelligent agent, selecting the best end, and reaching 

 it by the most appropriate means. "Invariably, however, when there 

 is plainly some final end to which a motion tends, should nothing stand 

 in the way, we say that such final end is the aim or purpose of the 

 motion."^ In other words, in the works of Nature, as in those of Art, 

 it is the desirability of the end, which in some way or other determines 

 the antecedent processes that lead to it. But you say, that what I call 



' Phys. ii, 8, 13. ^ -q p_ i ^ ^^ 3 p^yg. jj. g, 4. * Phys. ii. 8, 13. 



» D. G. V. 8, 4. « Phys. ii. 8, 15. ' Phys. ii. 8, 9. e d. P. i. i, 37. 



