One of the most profound insights of modern science is that nature has a symmetrical structure. Since antiquity, naturalists have observed bilateral symmetry in plants and animals, as well as symmetrical hexagons in ice and snow. In the 19th century, scientists looked through microscopes and saw that nature’s building blocks (cells, crystals) are arranged in symmetrical patterns and come in left-right pairs. In 1905, Albert Einstein discovered the symmetry of mass and energy – mass can be converted into energy and vice versa (E = mc2). He soon developed the general theory of relativity to give an accurate description of the cosmos from any frame of reference.