Paul Hazard on poetry at the hands of Realists in the late 1600s:
...If poetry is prayer, they never prayed; if it is reaching out towards the ineffable, they would not hear of the ineffable; if it is to hesitate on the delicate line betwixt music and meaning; they never hesitated; no, not they! They aimed at being just so many proofs and theorems. When they did write verse, it was merely a vehicle for their ideas on geometry."
|2013 NYRB edition|
The part that sticks out to me most are the lines about prayer and the ineffable. Poetry as a prayer to self, a personal god, the world, humanity. It rings with a kind of truth that I find hard to argue with.
This comes very near the end of Hazard's classic take down/history of the Enlightenment, The European Mind 1680-1715. The book is dense and catty. My knowledge of the Realists is not strong enough to agree or disagree with the thesis - That the Enlightenment may have put arts such as poetry on a back burner in favor of hard, cold reality.
I do think you could argue that while not poetry in its strictest sense, Voltaire, Locke, Spinoza, et al do reach a sort of poetic space by virtue of their ability with language. But it requires a very broad definition of poetry.
Here is Rousseau from Discourse on Inequality:
The first man who, having fenced in a piece of land, said "This is mine," and found people naive enough to believe him, that man was the true founder of civil society. From how many crimes, wars, and murders, from how many horrors and misfortunes might not any one have saved mankind, by pulling up the stakes, or filling up the ditch, and crying to his fellows: Beware of listening to this impostor; you are undone if you once forget that the fruits of the earth belong to us all, and the earth itself to nobody.
I put the parts I find most poetic in bold. This might help you see what I mean more clearly:
The first man,
a piece of land said,
This is mine
How many horrors
might one have saved
by pulling the stakes,
filling the ditch,
and crying out:
Beware this impostor;
you are undone to forget
the earth belongs
Nicolas-Charles-Joseph Trublet said in 1735:
"The earliest writers, we are told, were poets. That I can well believe; they could not very well have been anything else. But the latest will be philosophers."
I would argue there isn't a difference.