Yin And Yang
In Chinese philosophy, Yin And Yang describes how apparently opposite or contrary forces are actually complementary, interconnected, and interdependent in the natural world, and how they give rise to each other as they interrelate to one another. Many tangible dualities (such as; light and dark, fire and water, male and female) are thought of as physical manifestations of the duality. This duality lies at the origins of many branches of classical Chinese science and philosophy.
I usually find this symbol passé but reading into it makes it more appealing.