Not slavery so much. As with many large scale trends there are many large scale reasons. Massive income and wealth inequality kicked in around a hundred BC or

Not slavery so much. As with many large scale trends there are many large scale reasons. Massive income and wealth inequality kicked in around a hundred BC or so and poverty prevents a mass production consumer economy so right there you're limited to mass production of industrial goods, meanwhile if you have millions of times the wealth of a peasant there's nothing to spend the money on so you don't care about 0.1% rate of return vs 10% rate of return if there's not enough cool stuff to spend even 0.001% rate of return on. Their financial capital markets, nascent as they were, were essentially non-functional. If you know how to make a nationwide railroad, thats nice, but theres simply no way to finance it. There were no business/financial paths to wealth and anyone who became wealthy or powerful via trade was noteworthy and extremely rare; essentially all the people with money got it by sophistry or military skill, not by being intelligent stewards of their wealth, so expecting intelligent investment is overly optimistic. (edited in, lack of existing transport infrastructure means no commodities market, so flooding the local tin market just means you sell more tin for the same total revenue...) So in England at the start of the industrial revolution you had professional-ish mine managers who saw their only way to squeeze out that next percent of revenue was crazy coal powered steam engine water pumps... If a tin mine owning Roman wanted more tin, he'd just take over another province with some legions or legally wheel and deal his way into stealing a mine from a fellow Roman. Later on Diocletian codified central economic control, communist style, see the link. If you could make a steam locomotive engine, thats nice, but it would be illegal for anyone to work for you, especially the skilled craftsmen you'd need to assemble your locomotive. Have a small economic collapse now, or patch over things to produce a much bigger one later. Guess what option we selected this century for the last couple decades, LOL, the future for us is going to be almost as exciting as the Romans declining years... https://en.wikipedia.org/wiki/Diocletian#Social_and_professional_mobility https://en.wikipedia.org/wiki/Diocletian#Social_and_professi... Making a handwavy argument their civilization had reached and exceeded the scaling limit of an operational empire even for the most skilled emperors, and of course most emperors were not skilled. The point of that is increasing complexity increases fragility; a ridiculously complex economy based on silicon refined semiconductor computer technology would have collapsed much sooner, not later, and certainly not result in mobile phones in 1000 AD or whatever. If you thought Aurelian had problems with currency reform, imagine if that poor bastard had additional challenges of fractional reserve banking, high frequency trading, derivatives markets, financial alchemy such as mortgage based securities, if he had to put up with all that the poor guy would never have even tried...