If time is the factor of all progress by a necessary law, this necessity must be everywhere the same.  Have the elements of matter all the same age?  If so, why have some followed the law of progress, and others not?  Why has this mud and this coal remained mud and coal, age after age, while these other molecules have risen, in the hierarchy of the universe, to the dignity of life?  Why have these mollusks remained mollusks throughout the succession of their generations, while others, happily transformed, have gradually mounted the steps of the ladder up to man?  Whence comes this aristocracy of nature?  Are the beings which we call inferior only the cadets of the universe, and are they too in their turn to mount all the steps of the ladder?  Must we admit that there is going on the continual production, not only of living cellules which are beginning new series of generations, but also of new matter, which, setting out from the most rudimentary condition, is beginning the evolution which is to raise it into life?  They do not venture to put forth theses of this nature, and, in order to account for the diversity of things, recourse is had to circumstances.  The diversity of circumstances explains the diversity of developments.  But whence can come the variety of circumstances in a world where all is produced in the way of fatal necessity, and without the intervention of a will and an intelligence?  This is the remark of Newton.  Study carefully the systems of materialism:  their authors declare that to have recourse to God in order to account for the universe is a puerile conception unworthy of science, because all explanation must be referred to fixed and immutable laws; and then you will be for ever surprising them in the very act of the adoration of circumstances.  Convenient deities these, which they summon to their aid in cases which they find embarrassing.

But we will not insist on these preliminary considerations.  We have allowed, for argument’s sake, that all organized beings have proceeded by means of generation from cellules presenting to sensible observation similar appearances.  Natural history cannot prove, nor even attempt to prove, more.  Let us transport ourselves, in thought, to the moment at which the highest points of the continents were for the first time emerging from the primitive ocean.  We see, on the parts of the soil which are half-dried, and in certain conditions of heat and electricity, particles of matter draw together and form those rudiments of organism which are called living cellules.  These cellules have the marvellous faculty of self-propagation, and the faculty, not less marvellous, of transmitting to their posterity the favorable modifications which they have undergone.  Generations succeed one another; gradually they form separate branches.  New characteristics show themselves; the organisms become complicated, and becoming complicated they separate.  The vegetable is distinguished from the animal; the