Original: Apollodorus (reported by Diogenes Laertius, Lives of Eminent Philosophers, 10.14-15) gives his birth on the fourth day of the month February in the third year of the 109th Olympiad, in the archonship of Sosigenes As a boy he studied philosophy for four years under the Platonist teacher Pamphilus.
Simplified: As a boy he studied philosophy under the Platonist teacher Pamphilus for about four years.