Other posts on contraries include this.
Contrary opposites entail one another. There is no north without south or tall without short, for example. Some things such as sex are contraries in some respects but not in all respects.
Contrary opposites are symmetric. Contraries can be reversed or inverted, and they are still there. Since mirror opposites do not necessarily exist, mirror images are not contraries, though they exhibit a symmetry.
Because contraries entail one another and are symmetric, it is arbitrary to always prefer one to the other. One could just as well prefer the opposite contrary.
Contrary opposites can be unified into a higher perspective that contains them both. Unification is an expanded position that incorporates contraries.
Contrary opposites can be balanced in a duality that resists unification. A static equilibrium or dynamic harmony favors contrary opposites equally.
Ancient science prefers static contraries in balanced duality. Modern science prefers dynamic contraries in progressive unification.