Evidence of purposiveness is also furnished by the wonderful organs of adaptation, root-tips, leaves, eyes, lungs, etc. It is extremely improbable that they came into being--or even started to come into being--by mere chance alone. The odds are countless millions to one against the atoms, molecules, and cells--myriads in number--of any one of these organs of adaptation having by mere chance grouped themselves in such a way as to form an effective eye, or lung, or leaf. It is, literally speaking, infinitely improbable that the organs of adaptation we see in a forest, in plant and animal, should have come into existence through chance alone. The organs of adaptation are distinctly and definitely purposive structures--not purposed, perhaps, but certainly purposeful. In its struggle with its surroundings and with competitors the individual has been compelled to bring into being organs to fulfil a purpose. It is not the case that the organ was first created and then a use found for it, or use made of it. What actually happens is that first there is a vague but insistent reaching out towards an end, towards the fulfilment of some inner want or need--the need for food or to propagate, or whatever it may be--and that to achieve that end, or fulfil that need, the individual is driven to create a special organisation--as an Air Ministry was created during the War to fulfil the new need for fighting in the air--and so a new organ is produced: an essentially purposive structure such as the eye or the lung, though unpurposed before the need arose. The organs we see, therefore, are outward and visible signs of the existence within of a definite striving towards an end--that is, of a purpose. The forest shows an abundant, varied, and intense life in which individuals are for ever battling with one another. But all is not happening by chance. Everywhere we see signs of purposiveness. Purposiveness--the striving towards an end--stands out as a dominating feature in forest life. Selections and adaptations are made, but they are made with some purpose in view. Purpose governs the adaptations and selections. What that purpose is we shall try and discover as we get to know still more of Nature. * * * So far we have been observing individuals as separate individuals. Now we must look at them gathered together as a whole. And the first point we note is that though each individual has his own unique individuality, whether he be plant or man, all are kept together as a single whole. We have seen the individuals battling with one another, competing with one another, struggling against one another. But that is only one side of the picture. Just as remarkable as the way in which they have to resist one another is the way in which they depend on one another. Their interdependence is, therefore, the point we have now to note.