Greek philosopher Plutarch (c. 46 – 120 CE) attested the existence of Roman astronomers who rejected Aristotelian physics, "even contemplating theories of inertia and universal gravitation ", and suggested that gravitational attraction was not unique to the Earth. The gravitational effects of the Moon on the tides were noticed by Pliny the Elder (23–79 CE) in his Naturalis Historia and Claudius Ptolemy (100 – c. 170 CE) in his Tetrabiblos.