The Great Chain of Being
In their 1936 work, The Great Chain of Being: The History of an Idea, the scholars E. M. W. Tillyard and A. O. Lovejoy argued that ancient and medieval thought was shaped by particular ideological framework known as the "The Chain of Being." Sometimes called the Scala Natura (scale of nature), this view saw all of creation existing within a universal hierarchy that stretched from God (or immutable perfection) at its highest point to inanimate matter at its lowest. One can see something of this hierarchy in Plato's ranking of human souls in the Phaedrus, but also in Aristotle's notion that the capacity to act upon reason rather than instinct distinguishes human beings from animals.
Indeed, each link in the Great Chain of Being represented a distinct category of living creature or form of matter. Those creatures or things higher on the Chain possessed greater intellect, movement, and ability than those placed below. Thus each being in the Chain possessed all of the attributes of what was below plus an additional, superior attribute:
God: existence + life + will + reason + immortality + omniscient, omnipotent
Angels: existence + life + will + reason + immortality
Humanity: existence + life + will + reason
Animals: existence + life + will
Plants: existence + life
Matter: existence
Nothingness
As a result of this hierarchy, creatures and things on a higher level were believed to possess more authority over lower ones. Plants, for instance, were believed to have authority over the minerals in the soil. They were superior to minerals because, unlike inert matter, they were alive and capable of growth. Consequently, they had God’s sanction to draw nutrients from the earth and grow upon it, while the minerals and soil existed to support plants. Similarly, animals--a step higher on the Chain of Being--were thought to have authority over both inanimate plants and minerals. So horses could trod on rocks and earth and eat plants. Humans in turn were believed to possess greater attributes than animals. Thus it was proper for them to rule over the rest of the natural world. Similarly, spiritual beings like angels and God had greater ability than humanity and so ruled over and controlled humanity as well as the rest of the animal and the inanimate world.
This view of the world as a well-ordered hierarchy ordained by God was (and in some cases remains) enormously influential. It informed how people understood theology, science (especially astronomy), medicine, politics, and history.
The Great Chain of Being