I think what was missing was theory - numeric systems, chemistry, electromagnetism and other sciences. In the Roman era science wasn't invented yet - they wer

I think what was missing was theory - numeric systems, chemistry, electromagnetism and other sciences. In the Roman era science wasn't invented yet - they were excellent craftsmen and sometimes Greeks produced excellent ideas, but there was also a lot of really bad ones and the facilities to weed out the bad ideas (peer review and scientific method) and propagate them (the printing press) weren't available yet.