[SunkenCiv]

[snip] Suetonius relates that an inventor approached the emperor with plans for a hoisting machine that would greatly reduce the need for manpower but was rebuffed with the reply, “I must feed my poor.” Vespasian feared the machine would exacerbate unemployment in a society already overrun by idlers and slaves. Labor saving devices such as the water wheel were not wanted and consequently were neglected until there was a significant decline in both the general population and the number of slaves late in the 4th century. But a society that does not use its inventors will eventually lose its inventors. [/snip]

Stanley David Gedzelman, The Soul of All Scenery: A History of the Sky in Art, link, see Chapter 3

http://www.sci.ccny.cuny.edu/~stan/skyart.html

https://arsendarnay.blogspot.com/2012/05/vespasian-jobs-over-machines.html

[Right_Wing_Madman]

Vespasian feared the machine would exacerbate unemployment in a society already overrun by idlers and slaves.

Also, Professor Peter Green points out in Hellenistic History and Culture:

It's not so much that slaves were available, which indeed they were. No, the ruling classes were scared, as the Puritans said, of Satan finding work for idle hands to do. One of the great things about not developing a source of energy that did not depend on muscle power was the fear of what the muscles might get up to if they weren't kept fully employed.