Euclid , says Proclus, was younger than Plato and older than Eratosthenes and Archimedes , the latter of whom mentions him. He was of the Platonic sect, and well read in its doctrines. He collected the Elements , put in order much that Eudoxus had prepared, completed many things of Theætetus, and was the first who reduced to unobjectionable demonstration the imperfect attempts of his predecessors.