The ancient Ayleids believed that Nirn was composed of four basic elements -- earth, water, air, and light -- and of these four elements, they believed the most sublime form of light was star light. The stars are our links to the plane of Aetherius, the source of all magical power, and therefore, light from the stars is the most potent and exalted of all magical powers. Another, rarer form of Aetherial fragment is called 'meteroic glass'. It is from such fragments that other rare Ayleid enchanted artifacts are crafted -- Welkynd Stones and Varla Stones.