Nothing can exist without its antithesis to balance it. Everything is made of energy. The two fundamental energies are outward moving and inward drawing. As above, so below. As within, so without.
Reality is relative and finite.
Truth is universal and eternal. Reality is a subjective experience and can be explained. The Truth is obvious, needs no explanation and can not be captured with words. Throughout the class we'll use 'truth' to mean relative truth and 'Truth' or 'Whole Truth' to mean what is universal and eternal. This is Spirit.