We speak of the three kingdoms: the animal, the vegetable and the mineral kingdoms, and every substance is classified into one of these.
The exact truth is there is but one kingdom, which is the mineral. The vegetable substances and animal combinations are made of mineral elements.
In a rough way we distinguish the mineral kingdom as those substances called elements, such as iron, sulphur, carbon, oxygen, hydrogen, sodium and the like.
These elements are unchangeable in themselves; they do not grow. The animal is made of mineral elements associated in certain proportions, such as albumin, carbon, lime, water, salt and the like. The vegetable kingdom consists of these various chemical combinations also.
Seed when planted extracts from the air and the earth the minerals and combines them into a plant which grows and has for its object the making of seeds to reproduce and perpetuate itself.
The plant has life but it has no spiritual or mental equipment and therein vegetable life differs from the animal life. The animal eats vegetable and animal flesh. Through the vegetable he gets the mineral necessary for his body building. Through the animal food he gets the mineral from the flesh he eats, which flesh was first of all built up through the vegetables the animal ate.
These are definite facts; there is no theory about them.
The human body analyzed and separated into something like a dozen substances, among which are water, which is three-fourths of the body's structure; carbon, lime, phosphorus, iron, potassium, salt and so on.
By reading a book on anatomy you can learn just exactly the proportions of the substances in the human body.
All these chemicals are formed in the shape of little cells, myriads of which are in the body. These cells are constantly being destroyed and new ones made to take their place.