Rubuta ci gaba don wannan sakin layi - An haifi Lorentowicz a Pabianice, a cikin tsakiyar Poland ta yau, a 1868, shekaru biyar bayan buɗewar Tashin Poland na 1863
wanda daga karshe sojojin Rasha suka murkushe shi. Iyayensa sun yi ƙaura zuwa tsakiyar Poland ta yanzu daga tsohuwar iyakar "Kresy" ta gabas, suna tserewa daga talauci da zalunci. Jan ya sami takardar shaidar makarantar sakandare a Płock ta hanyar karatun gida kuma ba da daɗewa ba ya tafi Faransa, inda ya zauna har zuwa 1903 kuma ya yi karatu a Sorbonne.