Plato's Criticism of Social Engineering

Plato thought that the producers in this society would have private property, they would have trade. He envisaged that one would start afresh in designing this new society. And he even at one point says, well, we'll have to send everyone over the age of ten out into the fields and start again with this new city. But it is true that his vision is that you have to start from the ground up and control the society as a whole.