Our body is often compared to a perfectly tuned machine, but the comparison is incorrect. It would be much better to regard a machine as a poor imitation of the body. A machine requires much more maintenance than the human body and does not last nearly as long.
Althoughscience can do much to reduce the discomfort of a person who is ill, it is usually the body itself that defeats the disorder; a doctor can at most assist the process.
It is almost inconceivable that the complex entity which is our body has developed from a single-celled organism in the course of millions of years of evolution. But each person also develops out of just one cell, and the embryo in the womb could be said to go through a shortened evolution in developing from a single cell into billions of.
For centuries the body has been used as a model in developing new apparatuses. A camera, for example, is very similar in many ways to the eye. Imitations are also made of parts of the body in order to be able to replace them if they are defective. Heart valves, for example, enable a person to live many years longer than would have been possible with defective valves. However, an artificial valve always works less well than a real one and will never be more than an imitation.