Complex sentence: After falling behind in his studies, Tsiolkovsky spent 3 years attending a library where Russian cosmism proponent Nikolai Fyodorov worked and came to believe that colonizing space would lead to the perfection of the human race, with immortality and a carefree existence.
Split into simpler sentences: After falling behind in his studies, Tsiolkovsky spent 3 years attending a library where Russian cosmism proponent Nikolai Fyodorov worked. He later came to believe that colonizing space would lead to the perfection of the human race, with immortality and a carefree existence.