To Tsiolkovsky must go the credit of being the first scientifically trained individual to recognize the reaction principle as the key to travel into space, and of initiating its supporting theory on a scientific basis. He began this process in 1883 in his manuscript "Izmenenie sily tyazhesti" (Modification of the Force of Gravity"), though he initially derived his inspiration from Verne's space novels, especially an 1875 Russian translation of his second lunar tale 'round the moon'.