X was born at Tudela, Navarre (now in Spain) in 1089. He was one of the most distinguished Jewish men of letters and writers of the Middle Ages. X excelled in philosophy, astronomy/astrology, mathematics, poetry, linguistics, and exegesis; he was called The Wise, The Great and The Admirable Doctor.

He led a life of restless wandering, which took him to North Africa, Egypt, the Land of Israel, Italy (Rome in 1140–1143, Lucca, Mantua, Verona), Southern France (Narbonne, Béziers), Northern France (Rouen), England (London, and Oxford in 1158), and back again to Narbonne in 1161, until his death.

X was immortalized in a poem by Robert Browning which began with the famous lines:
Grow old along with me!
The best is yet to be.

X?

Answer:

Rabbi ben Ezra.