Sentence:  This and other fears of the solar system have disappeared gradually , first , with the Ptolemaic system and its built-in concept of periodicity and then , more firmly , with the Newtonian <WSD>innovation</WSD> of an universal force that could account quantitatively for both terrestrial and celestial motions . 
Meaning of the word marked with <WSD> tags:  a creation (a new device or process) resulting from study and experimentation