In the early 5th century Greek artists began consciously to attempt to render human and animal forms realistically. This entailed careful observation of the model as well as understanding the mechanics of anatomy - how a body adjusts to a pose which is not stiffly frontal but with the weight shifted to one side of the body, and how a body behaves in violent motion. The successors to the archaic kouroi, mainly athlete figures, are thus regularly shown 'at ease', one leg relaxed, with a complementary shift in the shoulders, and the whole emphasized by contrasts of rigid and relaxed in limbs.
The new style is best expressed in the Parthenon marbles of about 450-435 BC but there was a preceding style of some importance - the Early Classical, sometimes called the Severe Style, which is exemplified in the sculptures for the Temple of Zeus at Olympia. Here the figures are mainly lifelike but drapery forms are plainer (a change from the archaic Ionian chiton to the more austere peplos for women), and there are deliberate attempts at depiction of emotion in faces and of different ages in rendering of bodies.
These innovations were foresworn by Phidias, in his design for the Parthenon, and replaced by a more idealized realism in which body forms were often more regular than in life, and heads, except for monsters like centaurs, seem passionless, calm. Dress, after the austerity of the Early Classical becomes dramatically realistic. But the Parthenon is the fullest expression of what is sometimes called the High Classical. It is in this period and style too that, in the following hundred years, many of the basic types for the Greek gods were devised, and these remained influential throughout antiquity.
The new realism could not be achieved by the old techniques of carving directly into a stone block, but had to be based on a modelling technique, building up the figures in clay on armatures, like a skeleton, and then copying into stone. The same technique was