Brinton.] -*■-'-" [May 1, 



of creation." I cannot see that any known facts justify such a statement. 

 Evolution is a matter of the past not of the future. We have nothing to 

 do with the "finish of creation," and it is not likely that we know any- 

 thing about it. Such a dogma has no place in scientific bodies. All we 

 know is, that of the many millions of organized species a few have devel- 

 oped into higher forms, while the immense majority have perished utterly. 

 We have no guarantee but that evolution has reached its acme and may 

 cease to-night. Let us hold it, therefore, as a fact of past time, not as a 

 dogma of faith regarding the future. 



Turning now to the question of the evening. What are the ultimate 

 factors or primary causes, so far as we can trace them, which liave influ- 

 enced and do influence the development of organic forms? For an 

 answer I turn to an expression once used by my teacher, Prof. James D. 

 Dana, whose name is a household word to every man of science. His sug- 

 gestive expression was, "The whole of Nature is bound in a straight- 

 jacket of mathematics." It means that we must go back to the purely 

 mechanical forces of the universe, if we would find the primary factors 

 of organic variation. The last speaker well said that mutability, 

 change, not permanence, is the law of organic life. He developed it 

 admirably in his references to the like and the unlike, and in his state- 

 ment that unlikeness is really the secret of advance. This theory, as 

 doubtless some will remember, was that brought forward with force and 

 beauty by the late eminent Dr. Pasteur in his remarkable papers on 

 Asymmetry as the source of change in both the organic and inorganic 

 worlds. Unquestionably he was right. Change is the law of the uni- 

 verse. It is no new perception of the thinking mind. Nigli two thou- 

 sand years ago the philosopher Heraclitus of Ephesus laid down the 

 principle, "All is flowing," ravra pet. No two organic forms are 

 alike, or can be alike. The son is never the image of his father ; 

 the plant never finds in its product the precise reproduction of itself. 

 You remember how Leibnitz amused the ladies of the court by liaving 

 them try to find two leaves of an oak which were alike. They tried in 

 vain. Never anywhere is uniformity or identity ; everywhere is indefi- 

 nite, infinite variability. 



What is the explanation of this? 



I ask your attention again to the mechanical principles of nature. To 

 them alone must we return when we search for primary agencies of 

 change. All organic and inorganic substances are constantly subject to 

 the innumerable forces which play upon them from all parts of the uni- 

 verse. Every atom of earth is influenced by each distant star. Con- 

 stantly each atom is bombarded by thousands, by millions of forces, and 

 its changes are the resultants of these. 



The primary laws of motion with which we are familiar in the Principia 

 of Newton are also the primary causes both of the permanence and the 

 variability of organic forms. His first law — that motion would continue 

 forever in the same direction unless interfered with by other motion in 



