The Greeks also built an amazing array of devices, including the first steam-engine - as an amusing toy. A few different choices by ancient scientists and rulers and history might have been quite different. We lost about 1500 years to the 'dark ages'. Guess we weren't ready to make the technological leap when so much slave labor was available and life was cheap...
Will Durant's opinion was that the Roman leaders were afraid that technological progress would destroy jobs. Some things never change.