Actually one sees marriages which illustrate both these ideas. The first may be seen operating in the vegetable kingdom; it may be traced in the position of two leaves on the same stem, one balancing the other and responding to the other. The second may be seen ruling in the animal world, where mates become attached to each other through propinquity, until something comes to disturb their lives together; and then, absent from one another, they forget each other and readily accept a new mate.