Before beginning, however, to analyze the artistic features of the temple, it will be useful to consider the building materials which a Greek architect had at his disposal and his methods of putting them together.  Greece is richly provided with good building stone.  At many points there are inexhaustible stores of white marble.  The island of Paros, one of the Cyclades, and Mount Pentelicus in Attica—­to name only the two best and most famous quarries—­are simply masses of white marble, suitable as well for the builder as the sculptor.  There are besides various beautiful colored marbles, but it was left to the Romans to bring these into use.  Then there are many commoner sorts of stone ready to the builder’s hand, especially the rather soft, brown limestones which the Greeks called by the general name of poros. [Footnote:  The word has no connection with porous] This material was not disdained, even for important buildings.  Thus the Temple of Zeus at Olympia, one of the two most important religious centers in the Greek world, was built of local poros.  The same was the case with the numerous temples of Acragas (Girgenti) and Selinus in Sicily.  An even meaner material, sun-dried brick, was sometimes, perhaps often, employed for cella walls.  Where poros or crude brick was used, it was coated over with a very fine, hard stucco, which gave a surface like that of marble.

It is remarkable that no use was made in Greece of baked bricks before the period of Roman domination.  Roof-tiles of terra-cotta were in use from an early period, and Greek travelers to Babylonia brought back word of the use of baked bricks in that country.  Nevertheless Greek builders showed no disposition to adopt baked bricks for their masonry.

This probably hangs together with another important fact, the absence of lime-mortar from Greek architecture.  Lime-stucco was in use from time immemorial.  But lime-mortar, i.e., lime mixed with sand and used as a bond for masonry, is all but unknown in Greek work. [Footnote:  The solitary exception at present known is an Attic tomb built of crude bricks laid in lime-mortar] Consequently in the walls of temples and other carefully constructed buildings an elaborate system of bonding by means of clamps and dowels was resorted to.  Fig. 46 illustrates this and some other points.  The blocks of marble are seen to be perfectly rectangular and of uniform length and height.  Each end of every block is worked with a slightly raised and well-smoothed border, for the purpose of securing without unnecessary labor a perfectly accurate joint.  The shallow holes, III, III, in the upper surfaces are pry-holes, which were of use in prying the blocks into position.  The adjustment having been made, contiguous blocks in the same course were bonded to one another by clamps, I, I, embedded horizontally, while the sliding of one course upon another was prevented by upright dowels, II, II.  Greek clamps and dowels were usually of iron and they were fixed in their sockets by means of molten lead run in.  The form of the clamp differs at different periods.  The double-T shape shown in the illustration is characteristic of the best age (cf. also Fig. 48).