Your ego, your desires, your aims and ambitions.

If you were a pile of stones then your ego, drives, ambitions, aims etc would be the topmost ones.

Those sit upon other stones that represent something deeper, an entrenched system within you.

A special layer.

The large bottom stone could represent your biology.

Between the biology and the psychology is that special layer.

Psychology - aims, drives, ambitions, wants, desires, hopes, dreams.

Special layer

Biology

Whilst our ego, our desires, our ambitions, differ from person to person ...

... this special layer is the same in all of us.

Understanding it will help with your ego, your ambitions and any interest in psychology.