He once saved Alexander's life by discovering and revealing a dangerous conspiracy which had been formed against the king.

Alexander had the opportunity to requite this favor, through a divine interposition vouchsafed to him, it was said, for the express purpose of enabling him to evince his gratitude.

Ptolemy had been wounded by a poisoned arrow, and when all the remedies and antidotes of the physicians had failed, and the patient was apparently about to die, an effectual means of cure was revealed to Alexander in a dream, and Ptolemy, in his turn, was saved.
At the great rejoicings at Susa, when Alexander's conquests were completed, Ptolemy was honored with a golden crown, and he was married, with great pomp and ceremony, to Artacama, the daughter of one of the most distinguished Persian generals.
At length Alexander died suddenly, after a night of drinking and carousal at Babylon.

He had no son old enough to succeed him, and his immense empire was divided among his generals.

Ptolemy obtained Egypt for his share.