There are many reasons why soil, our main resource for life besides water, is known as the "living skin of the earth."
Soil gives us not only the source of plant life, but provides material for buildings, homes for animals, and even medicine from its bacteria.
Topsoil, sand, silt, and clay are the components of soil, and the most dominant determine the health and growth of plants. Topsoil, a vital ingredient, is composed of remains of dead animals and decayed plants.
Millions of years of rain and the erosion of mountains have given us rocks which have broken down into grains of different sizes to form our soil.
Sand, composed of larger grains not closely joined, allows water to slip through, preventing roots from holding proper nutrients, and below that, silt, which is composed is smaller grains, holding more water.
Finally, clay, a composition of tiny rocks joined closer together, holds on to water and cannot be washed away like sand and silt. This is why it is used for pottery and the construction of buildings. Add compost - decayed food and grass - to all of the above for healthy plants.
An extremely important provider of nutritious soil is actually the cow. After chewing up and digesting plants, the material that is processed and formed in its body becomes you-know-what: manure. After it has thoroughly dried and is broken up, put your seeds into that and just watch the miraculous growth.