THE P H E N O M E N O N OF M A N
THE ADVENT OF LIFE
A moment ago I reminded the reader that many terrestrial transformations which we could have sworn had stopped, and stopped ages ago, are still going on in the world around us. Under the influence of this unexpected observation which pampers our natural preference for palpable and manageable forms of experience, our minds are inclined to slide gently into the belief that there never was in the past or will be in the future anything new under the sun. And it would only be one step farther to limit full and real knowledge to the events of the present. Fundamentally, is not everything, apart from the present, mere ' conjecture ' ? We must at all costs resist this instinctive limitation of the rights and scope of science. No. The world would not f d y satisfy the conditions imposed by actuality-it would not be the great world of mechanics and biology-if we were lost in it like ephemeral insects which are unaware of all save their brief season. So vast are the dimensions of the universe disclosed by the present that, for this reason alone, all sorts of things must have happened in it before man was there to witness them. Long before the awakening of thought on earth, manifestations of cosmic energy must have been produced which have no parallel today. Thus, besides the group of phenomena subject to direct observation, there is for science a particular class of facts to be considered-specifically the most inlportant because the rarest and most significant-those which depend neither on direct observation nor experiment, but can only be brought to light by a very authentic branch of ' physics ', the discovery ofthe past. And, to judge by our repeated failures to h d its equivalent around us or to reproduce it, the fmt apparition of living bodies is clearly one of the most sensational of these events. With that, let us advance a step. There are two possible ways in which something can fail to coincide, in time, with our power ofseeing. One is for it to happen at such distant intervals that the whole of our existence can run its course between two successive occurrences. The other, by which we miss it still more inevitably, is for it to have happened once and never be repeated. In other
words, either a recurrent phenomenon of very infrequent periodicity (such as we meet so often in astronomy) or one strictly unique (as with Socrates or Augustus in human history). In which of these two ' inexperimental' or rather ' praeterexperimental ' categories do we find it most suitable, in the light of Pasteur's discoveries, to put the birth of life, the initial formation of cells from matter ? There is no lack of facts to support the idea that organised matter might germinate periodically on the earth. Later on, when I come to o u h e the ' tree of life ', I shall be calling attention to thc coexistence in the living world of certain large aggregates (protozoa, plants, hydrozoa, insects, vertebrates) whose lack of basic relationship might be fairly satisfactorily explained in terms of heterogenous origins. Something like those successive intrusions going back to different ages originating from the same magma, whose interlacing veins form the eruptive complex of a single identical mountain . . the hypothesis o f independent vital pulsations would conveniently account for the morphological diversity of the principal sub-kingdoms recognised by systematic biology. Moreover, there is no difficulty on the chronological side. In any case the length of time separating the historical origins of two successive subkingdoms is much greater than the age of mankind. So it is not astonishing that we should live in the illusion that nothing happens any more. Matter seems dead. But could not the next pulsation be slowly preparing around us ? I f e l bound to point out and even, to a certain extent, to defend the conception of a spasmodic genesis of life. Yet I cannot actually adopt it. For there is one decisive objection against the idea of a number of different, successive, vital thrusts on the earth's surface-namely the fundamental similarity of all organic beings. We have already called attention in this chapter t o the curious fan that all molecules of living substances are asymmetrical in the same way, and contain precisely the same vitamins. Now, the more complex organisms become, the more evident becomes
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