The meninges (from the Greek meninx, meaning membrane) cover and protect the brain and spinal cord. The meninges have three layers: 1) the dura mater, 2) the arachnoid, and â¦ 3) the pia mater. The dura mater is the outermost layer covering the central nervous system.he innermost layer of the meninges is the pia mater. The pia mater is firmly attached to the neural tissue of the spinal cord and brain. Cerebrospinal fluid fills the space between the pia matter and the arachnoid membrane. Most of the blood vessels that supply blood to the central nervous system are in the pia mater.
According to Aristotle, tragedy has six main elements: plot, character, diction, thought, spectacle (scenic effect), and song (music), of which the first two are primary.
Aristotle believed that all bodies are made up of four elements: earth, water, air and fire (see Fig. 2.7). These elements naturally move up or down, fire being the lightest and earth the heaviest. A composite object will have the features of the element which dominates; most things are of this sort.