These ‘primary’ entities were identified in I Ching and discussed by many Chinese Philosophers. In I Ching, the universe is represented by eight trigrams (pa-qua). Each trigram consist of 3 strokes that can be whole or broken (state). Two to the power of three gives eight which represents all possible combinations. The top stroke represents the heaven, the bottom is earth with human in the middle. I Ching is used in Chinese Feng Sui as well as fortune telling.

If you take away the myth, these concepts can be a very relevant way of viewing ourselves and our surroundings:
Heaven 天 – the Chinese character represent the sky, god or heaven. It represents factors and talents given at birth like your genes, when and where you are born, how tall you are, who your parents are does not change. It also represents the Law of Nature and maybe even random chance.

Earth 地 – the Chinese character means ground, land or earth. It is intended to represent resources and environmental factors. It can foster growth and can give you functional advantages e.g. caves against wind and rain, high vantage points to improve visibility, amount and angle of sunlight, etc.

Mankind 人 – the Chinese character means human being or mankind. i.e. you and people around you. It represents the many actions, effort, decisions, interactions that are under your control and influence. While human cannot change what is given to him, he can change how he view it and hence how he uses those as opportunities.

I don’t believe a person’s destiny is totally predetermined at birth. Free will is something given to us and it is up to us to make the best out of what is given.

Perfect circumstances involves the right time (opportunity), right place and the right person(s) (天時、地利、人和). Working against natural factors often lead to disastrous results. For example, during World War II, despite their military might, the Germans were defeated by the harsh Russian winter. Or the rise of communism in China became a possible solution when corruption was rampant within the government while the rest of the people suffers.

Exercise
How is this related to martial arts?

Heaven, earth and mankind 天地人