It must be remembered that all good art means slow work--long thinking, much experiment, tedious attention to detail in plan, and careful execution. Meanwhile men have to live, even immortal artists, and rarely indeed does one undertake a work of importance on his own account. It is true that in the greater days of Greece the best artists were almost entirely employed by a State, or at least to execute works for public exhibition, and doubtless the payment they received was quite a secondary matter with them, but nevertheless few could practise their art without remuneration. During the fifth and fourth centuries great events were constantly happening in Greece, and in consequence there were numberless temples to build and adorn, groves to decorate, men to honour, and monumental tombs to erect. Innumerable statues of gods and goddesses were wanted, and we must not forget the wholesale destruction of Athenian and other temples and sculptures during the Persian invasion. In fact for a century and a half after Platæa, there was practically an unlimited demand for works of art, and it was only when the empire of Alexander began to crumble away that conditions changed. While Greece was weakening Rome was growing and her lengthening shadows were approaching the walls of Athens. Greece could build no more temples when her people were becoming slaves of Rome; she could order no more monuments when defeat was the certain end of struggle. And so the decline was brought about, not by want of artists, but through the dearth of orders and the consequent neglect of competition.