The organic cycle describes the natural cycle of consumption, growth, decay, and death that occurs in living systems. To simplify the process and reach a solid baseline understanding, you can look at it as having four main aspects: Soil/Microorganisms, Plants, Animals, and Man.

The soil is the foundation of the organic cycle (literally and figuratively), as it contains the microorganisms that recycle all other organic "matter" and allow it to be transformed into living organisms once again.

Plants feed directly on the nutrients present in the soil and also draw water from under the ground to meet their biological needs. If the nutrient profiles are good in the soil, so will the quality of life of the plants in that area. Plants also grow towards the Sun, as they utilize the powerful electromagnetic energy from it to initiate their process of energy production in their cells (photosynthesis). When plants decay and die, their components return to the soil to be broken down and transformed into new life later.

Many animals feed directly on plants, and so the nutrients that originated in the soil have now moved from the plants to them. There is a huge diversity of animals- with some feeding exclusively on plants (herbivores), some feeding almost exclusively on other animals (carnivores), and some feeding on a combination of both (omnivores). However, all animals must draw their resources from other organisms and cannot directly use the Sun's energy to meet all of their biological needs. Similar to plants, when animals die, their body parts decay and return to the soil.

Finally, there are humans- the most controversial aspect of all in this cycle. Humans could be classified as another type of animal, but we are getting our own category because of our unique intelligence and ability to influence all other aspects of the cycle. Humans obviously feed on both plants and animals, and our intelligence (and advanced technologies) enables us to dictate the course of many other species and even degrade the environment around us. That said, when our bodies die, we ultimately return to the soil and are a part of the cycle like everything else (excluding cremations and other ceremonies that we do nowadays).

With this basic understanding, we can see how all life feeds on other life and gain an appreciation for how what we do can affect the living environment all around us.