In attempting to know, we engage in grand and meaningful acts. We use our human brains as time machines, to see and learn from the distant past and to travel forward thousands, millions, and billions of years. This young, patchwork organ that evolved to help ancient primates find food and water, maintain group relationships, achieve sexual intercourse, and imagine the next best tool now carries us to the very ends of the universe and beyond.

It is essential to understand our brains in some detail if we are to assess correctly our place in this vast and complicated universe we see all around us.

Given for one instant an intelligence which could comprehend all the forces by which nature is animated and the respective situation of the beings who compose it—an intelligence sufficiently vast to submit these data to analysis—it would embrace in the same formula the movements of the greatest bodies of the universe and those of the lightest atom; for it, nothing would be uncertain and the future, as the past, would be present to its eyes. The human mind offers, in the perfection which it has been able to give to astronomy, a feeble idea of this intelligence. Its discoveries in mechanics and geometry, added to that of universal gravity, have enabled it to comprehend in the same analytical expressions the past and future states of the system of the world.

To express this increasingly complex subject as succinctly as possible, the ancestors of our species developed the brain power to connect with other minds and to conceive unlimited time, distance, and potential outcomes. This infinite reach of imagination, put quite simply, is what made us great.

We are a way for the cosmos to know itself

Look at its power,' he continued. 'Five thousand years on it still gets you. It involves you whether you like it or not … It forces you into a process of thinking … forces you to learn. The minute you ask a question about it you've asked a question about engineering, you've asked a question about geometry, you've asked a question about astronomy. So it forces you to learn about engineering and geometry and astronomy, and gradually you begin to realize how sophisticated it is, how incredibly clever and skilful and knowledgeable its builders must have been, which forces you to ask questions about mankind, about human history, eventually about yourself too. You want to find out. This is the power of the thing.

We are a way for the cosmos to know itself.

Even the heavens are open to the mind of Man. Man alone of all the animals has traced the pathways of the rising and the setting of the stars. Man has measured out the days and months and years. Man alone has understood and can predict the eclipses of the sun and moon for all future time, when they will occur, and whether they will be partial or total. When the mind contemplates these phenomena, it learns also knowledge of the gods. So religion is born, and with it goodness and all the virtues which make up the good life, a life which reflects the divine life. We need to be inferior to the gods in nothing except our mortality, which need in no way hinder us from living well. In explaining these things, I think that I have shown clearly enough how much superior is human nature to that of all the other animals. From which we must infer that such a shape and arrangement of our limbs and such a power of intelligence cannot have been the work of chance alone.