The Greeks had long kept certain more or less formal relations with the people of Macedonia . The Macedonians from their side had kept themselves well informed about conditions in Greece.  Now it happened, just when Sparta and Athens had finished their disastrous war, that Macedonia was ruled by an extraordinarily clever man named Philip. He admired the Greek spirit but he looked down on the Greek lack of self-control in political affairs. It angered him to see a perfectly good people waste its men and money upon fruitless quarrels. So he settled the difficulty by making himself the master of all Greece and then he asked his new subjects to join him on a voyage which he meant to pay to Persia in return for the visit which Xerxes had paid the Greeks 150 years before.  Unfortunately Philip was murdered before he could start this well-prepared expedition . The task of avenging  the destruction of Athens was left to Philip's son Alexander, the beloved pupil of Aristotle, wisest of all Greek teachers.  Alexander left Europe in the spring of 334 BC. Seven years later he reached India. In the meantime he had destroyed Phoenicia(,), the old rival of the Greek merchants. He had conquered Egypt and had been worshipped by the people of the Nile valley as the son and heir of the Pharaohs . He had defeated the last Persian king -- he had overthrown the Persian Empire, he had given orders to rebuild Babylon -- he had led his troops into the heart of the Himalayan mountains and had made the entire world a Macedonian province and dependency. Then he stopped and announced even more ambitious plans.  The newly formed Empire must be brought under the influence of the Greek mind. The people must be taught the Greek language -- they must live in cities built after a Greek model. The Alexandrian soldier now turned school-master. The military camps of yesterday became the peaceful centres of the newly imported Greek civilisation. Higher and higher did the flood of Greek manners and Greek customs rise, when suddenly Alexander was stricken with a fever and died in the old palace of King Hammurabi of Babylon in the year 323BC.  His Empire did not long survive him. A number of ambitious generals divided the territory among themselves. But they too remained faithful to the dream of a great world brotherhood of Greek and Asiatic ideas and knowledge. They maintained their independence until the Romans came. It can be implied that Philip organized a voyage to Persia_.
to pay a return visit to avenge the destruction of Athens to start a well-prepared expedition to spread Greek culture