Adam Smith on emergent opulence: peace, easy taxes and justice

You heard it first from Thucidides. Now here’s Smith:

Little else is requisite to carry a state to the highest degree of opulence from the lowest barbarism, but peace, easy taxes, and a tolerable administration of justice; all the rest being brought about by the natural course of things. All governments which thwart this natural course, which force things into another channel, or which endeavour to arrest the progress of society at a particular point, are unnatural, and to support themselves are obliged to be oppressive and tyrannical.

Adam Smith – Lecture Notes (?)

Questions for Smith:

Is opulence the opposite of barbarism? It sounds a bit like decadence to me. Is there a virtuous mean that we could aim for instead? (“Purposeful prosperity”?)

Define “easy taxes”.

Define “justice.”

Is the “natural course of things” always equivalent to “the progress of society?”

Hat tip: Lex Fridman

I'd love to hear your thoughts and recommended resources...