417. 'Anyone can, if he wishes, convince himself in favour of Divine origin by observing nature, and he can also do so if he thinks about God from observation of life. For instance, when he observes the birds of the air, and sees how each species knows what to eat, and where it is to be found. It recognises its kind by sound and sight; and in other species knows which are friends and which enemies. He sees that they pair, know how to mate, construct skilful nests, lay eggs in them, and sit on these; they know how long they take to hatch, and at the end of this period they hatch their chicks, which they love most tenderly, keeping them under their wings, offering food and feeding them. They continue doing this until they are able to fend for themselves and can do the same, bringing up a family to secure their permanence of the race.
Everyone who is willing to think about the way the Divine influence passes through the spiritual world into the natural one can see this in those facts. He can even, if he is willing, say in his heart, "Such knowledge cannot reach them from the sun by the radiation of its light. For the sun, from which nature arises and draws its essence, is undiluted fire, so that the rays of its light are totally devoid of life." Thus they reach the conclusion that such things are the result of Divine wisdom influencing the lowest forms of nature.