Although Ptolemy II later married his sister Arsinoe in the Egyptian tradition, his first wife is also named Arsinoe (It’s nearly impossible to keep them all separate!). Historians call his first wife Arsinoe I and his sister Arsinoe II in an effort to differentiate them. It was his first wife who bore him his children, Ptolemy III (his successor), Lysimachus (who is named after his mother’s father), and a daughter named Berenike. His sister/wife Arsinoe II doesn’t seem to have borne him any children. Philadelphus had two half-brothers, Ptolemy Keraunos and Meleager, sons of Ptolemy Soter from a previous marriage. Both became kings in Makedonia. When Philadelphus was young, he was educated by Philitas of Kos, who was a well-known scholar and poet, and the philosopher Strato of Aristotle’s school, which instilled him what would become a lifelong love of learning.
In 88 BCE he began to rule as co-regent with his parents Ptolemy Soter and Berenike I. Three years later, when Ptolemy Soter was sure that his son was ready to rule on his own, Philadelphus took over. Philadelphus was not a great warrior, he was a peaceable and cultured king, who was eager to increase the literary works in the great Library and to patronize scientific research. He loved to be in the company of philosophers, poets, and scientists. He was a “lover of all that is beautiful and of literature.” Zenodotus, the man who he appointed as bibliophylax, or “Custodian of the Books”, invented alphabetization as a way to organize books and created the first modern library shelving system. Kallimakhos, Theocritus, and a host of lesser-known poets glorified the Ptolemaic dynasty and recorded their works. Philadelphus also finished the building of the Pharos lighthouse, one of the 7 wonders of the ancient worked, started by his father. Philadelphus was a great ruler, who continued his father’s work of uniting the Egyptian and Greek peoples.
While they were still living Philadelphus and Arsinoe declared themselves living Gods, and they were called the Theoi Adelphoi, “the Brother-Sister Gods”. Ever after the Ptolemies would be worshiped as God-kings in the Egyptian manner. Even in her lifetime Arsinoe was being prayed to, particularly by sailors, suggesting she was seen as a kind of avatar of Isis.
Philadelphus also took the Egyptian name Meryamun Setepenre, which means “Beloved of Ammon, Chosen of Ra”. (another source says the name was Weserkare Meryamun “Powerful is the soul of Ra, beloved of Ammon”.) It was under Philadelphus that Alexandria really began to grow. It grew so fast under Ptolemy II and Ptolemy III that it had to be divided into three districts, making them easier to govern. By the end of his reign, it consisted of Rhakotis, the native Egyptian quarter (and the original village before Alexandria was built), Bruchium, the Greek-Makedonian quarter and the Jewish Quarter, which was almost as big as the Greek section. Philadelphus completed a canal from the Nile River to the Gulf of Suez. The canal been started under the last Egyptian Pharaoh, but was forced to be abandoned when Darius became the Persian King. It was named Ptolemy River in honor of the man who finished it. Many say that under Ptolemy II Philadelphus Egypt attained its greatest height.
Philadelphus was a fervent worshiper of Dionysos, and sponsored many elaborate and expensive festivals in the God’s honor. He bought many exotic animals from faraway lands, to live in a kind of Alexandrian zoo. In fact, in one of the more elaborate processions in honor of Dionysos, there were 24 chariots drawn by elephants and followed by pairs of lions, leopards, panthers, antelopes, wild asses, camels, a bear, a giraffe, a rhinoceros, and as many as 8 pairs of ostriches. One of chariots was drawn by elephants and carried a 7-foot call solid gold statue of Dionysos. Perhaps appropriate for a worshiper of Dionysos, Philadelphus was famous for his many mistresses and concubines.
But he was also a great ruler, perhaps even better than his father. Ptolemy Soter had vision, but was bored by some of the day-to-day efforts it took to run a county like Egypt. He left the details to his advisors. Philadelphos threw himself into it and learnt the ins and outs of everything, so he knew intimately what was going on, which also meant that his advisors would not be able to trick or cheat him. He even invented new currency, changing the relatively primitive barter system the Egyptian used into a more modern banking system, according to The Rise and Fall of Alexandria: Birthplace of the Modern World, by Justin Pollard and Howard Reid (which I plan to review whenever I finish reading it). I’ll end this post with a quote from Philo:
“In all the qualities which make a good ruler, Ptolemy Philadelphos excelled not only his contemporaries, but all who came before him so that even today, after so many generations, his praises are sung for the many evidences and monuments of his greatness of mind which he left behind him in different cities and countries. That is why acts of more than ordinary munificence or buildings on an especially great scale are proverbially called Philadelphian after him. … To put it shortly, as the house of the Ptolemies was highly distinguished, compared with other dynasties, so was Philadelphos among the Ptolemies. The creditable achievements of this one man almost outnumbered those of all the others put together, and, as the head takes the highest place in the living body, so he may be said to head the kings.” – Philo, Life of Moses 2.29-30
 Scullard, H.H The Elephant in the Greek and Roman World Thames and Hudson. 1974 pg 125 “At the head of an imposing array of animals (including…)”