I have read Carlyle's 1830 essay on history with its famous paragraph :
Before Philosophy can teach by Experience, the Philosophy has to be in readiness, the Experience must be gathered and intelligibly recorded. Now, overlooking the former consideration, and with regard only to the latter, let anyone who has examined the current of human affairs, and how intricate, perplexed, unfathomable, even when seen into with our own eyes, are their thousand-fold blending movements, say whether the true representing of it is easy or impossible. Social Life is the aggregate of all the individual men's Lives who constitute society; History is the essence of innumerable Biographies. But if one Biography, nay, our own Biography, study and recapitulate it as we may, remains in so many points unintelligible to us, how much more must these million, the very facts of which, to say nothing of the purport of them, we know not, and cannot know!
I can readily see how, from a methodological individualist perspective, Carlyle might suppose that institutions, customs, practices, social objects of all kinds, might be reducible to the interactions of (innumerable) individuals. What I cannot see is the point of that word, 'essence'. Why not just say History is the sum of innumerable Biographies or even History is reducible to, is nothing but, innumerable Biographies ?
I may be handicapped by being a philosopher : 'essence' is a problematic notion in the trade but I don't suppose that Carlyle used 'essence' in any philosophically technical sense. I am not raising a casual question without research. I have read much of Caryle - nothing like all - but I have never been able to persuade myself that I understood what 'essence' is doing here.
Historians are much likely than I am to give an informed explanation.