Is evolution a theory, a system or a hypothesis? It is much more: it is a general condition to which all theories, all hypotheses, all systems must bow and which they must satisfy henceforward if they are to be thinkable and true. Evolution is a light illuminating all facts, a curve that all lines must follow.

A glow ripples outward from the first spark of conscious reflection. The point of ignition grows larger. The fire spreads in ever widening circles till finally the whole planet is covered with incandescence. Only one interpretation, only one name can be found worthy of this grand phenomenon. Much more coherent and just as extensive as any preceding layer, it is really a new layer, the 'thinking layer', which, since its germination at the end of the period, has spread over and above the world of plants and animals. In other words, outside and above the biosphere there is the .

Discontinuity in continuity: that is how... the birth of thought, like that of life, presents... and defines itself.

Those who adopt the spiritual explanation are right when they defend... a... transcendence of man over the rest of nature. But neither are the materialists wrong when they maintain that man is just one further term in a series of animal forms. Here, as in so many cases, the two antithetical kinds of evidences are resolved in a movement... to the highly natural... 'change of state'. From the cell to the thinking animal, as from the atom to the cell, a single process (a psychical kindling or concentration) goes on without interruption... in the same direction. But by virtue of this permanence in the operation, it is inevitable... that certain leaps... transform the subject of the operation.

When water is heated to boiling... and one goes on heating it, the first thing that follows—without change of temperature—is a tumultuous expansion of freed and vaporised molecules. Or, taking a series of sections from the base towards the summit of a cone, their area decreases constantly; then suddenly, with another infinitesimal displacement, the surface vanishes leaving us with a point. Thus... we are able to imagine the mechanism involved in the critical threshold of reflection. ...[N]ervous systems followed pari passu the process of increased complication and concentration. Finally, with the primates, an instrument was fashioned so remarkably supple and rich that the step immediately following could not take place without the whole animal psychism being... recast and consolidated on itself. ...When the anthropoid... had been brought 'mentally' to boiling point.... Or... had almost reached the summit of the cone, a final effort took place along the axis. ...What was previously only a centred surface became a centre. By a tiny 'tangential' increase, the 'radial' was turned back on itself and... took an infinite leap forward. Outwardly, almost nothing in the organs had changed. But in depth, a great revolution... consciousness was now leaping and boiling in a space of super-sensory relationships and representations; and simultaneously... was capable of perceiving itself... for the first time.

We realise... the fact and... reason for the diversity of animal behaviour. From the moment we regard evolution as... psychical transformation, we see... a multitude of forms of instincts each corresponding to a... solution of the problem of life. The 'psychical' make-up of an insect is not and cannot be that of a vertebrate ; nor can... that of a squirrel be that of a cat or... elephant: this in virtue of the positions... on the tree of life. ...We begin to see ...a gradation formed. If instinct is a variable dimension, the instincts will... create, beneath their complexity, a growing system. They will form as a whole a... fan-like structure in which the higher terms on each nervure are recognised... by a greater range of choice and depending on a better defined centre of coordination and consciousness. ...The 'psychical' make-up of a dog... is... superior to that of a mole or a fish. ...The upholders of the spiritual explanation have no need to be disconcerted when they see... in the higher animals (particularly in the great apes) ways and reactions which strangely recall... 'a reasoning soul'. If the story of life is no more than a movement of consciousness veiled by morphology, it is inevitable that... in the proximity of man, the 'psychical' make-ups seem to reach the borders of intelligence.

To the cosmic corpuscles we should find it natural to attribute an individual radius of action as limited as their dimensions. We find, on the contrary, that each of them can only be defined by virtue of its influence on all around it. Whatever space we suppose it to be in, each cosmic element radiates in it and entirely fills it. However narrowly the heart of an atom may be circumscribed, its realm is co-extensive, at least potentially, with that of every other atom. This strange property we will come across again, even in the human molecule.

Sometimes we need bread, sometimes wine, sometimes a tonic or a hormone injection, sometimes the stimulation of a colour, sometimes the magic of a sound which goes in at our ears as a vibration and reaches our brains in the form of inspiration. ...There is something through which material and spiritual energy hold together and are complementary. ...There must be a single energy operating in the world. ...The 'soul' must be ...a focal point of transformation ...Forces of bodies converge, to become interiorised and sublimated in beauty and truth. ...Yet, ...direct transformation of one of these two energies into the other... has to be abandoned. As... we try to couple them... their mutual independence becomes as clear as their interrelation.

To connect the two energies, of the body and the soul, in a coherent manner: science has provisionally decided to ignore the question... caught up as we are here in the logic of a system where the within of things has just as much or... more value than their without... we must advance.

Nowhere... is the need more urgent of building a bridge between the... the physical and the moral...