He trained to be an engineer at the École Centrale in Paris from 1902 to 1905 and there attended lectures by Emile Picard and Paul Appell . However, not being a French citizen he would have found great difficulty obtaining an academic post in France. Fully understanding this, in November 1905 at the age of 21, Lefschetz went to the United States.
Siya ay sanay na sa isang engineer sa École Centrale sa Paris 1902-1905 at pumasok sa lektura sa pamamagitan ng Emile Picard at Paul Appell. Gayunman, hindi na isang French citizen siya ay natagpuan sa dakilang paghihirap ng isang academic-post sa France. Ganap-unawa na ito, noong Nobyembre 1905 sa edad na 21, Lefschetz nagpunta sa Pilipinas.