Grabowski was born in Nowe Dobra, a village 10 km northeast of Chełmno. Soon after his birth, the family moved from Nowe Dobra to Thorn, Prussia (now Toruń, Poland). Due to his parents' poverty, Grabowski had to start working soon after leaving elementary school. Nevertheless, he prepared himself, driven by a great desire to learn, to take the entrance exam for grammar school (Gymnasium), which he passed with flying colours. At the Copernicus School in Thorn, after demonstrating a knowledge far exceeding others of his age, he twice skipped a grade. In 1879, the family's financial situation improved and, after his Abitur exam, Grabowski studied philosophy and natural science at the University of Breslau in Breslau (now Wrocław).