The special relationship between Syracuse and Egypt focused on trading relations and significant political and cultural interaction, started in the 4th century BC and reached its peak under Hiero II, who adopted the Ptolemy kingdom as a model for his State. Even the lex hieronica was inspired by the Ptolemaic tax system. The coin portrait of Queen Philistides with a veiled head was inspired by those of Queens Arsinoe and Berenice II on Ptolemaic coins. The system of silver coin emission was also based on a Ptolemaic model. Close relationships in arts and religious influences emanated from the outstanding cultural city of Alexandria, where Archimedes and the Syracusan poet Theocritus spent long periods. These were extensively embraced by Sicily after crossing that Mediterranean Sea on which both powers kept a constant focus.