The history's ladder: (i) the ancient-and-medieval faces — Aristotle's constitutions' comparison; the Roman-law's and canon-law's interplay; (ii) the 18th-19th century birth — Montesquieu's comparative spirit (De l'Esprit des Lois, 1748); the 1900 Paris Congress (the discipline's formal birth — Saleilles-and-Lambert's program: the "comparative legislation"
movement); (iii) the 20th-century growth — the institutes-and-journals' founding; the interwar- and-postwar expansion (the UN-and-UNIDROIT's unification work); the socialist-and-developing systems' entry (the cold-war-era comparisons); (iv) the modern era — the European integration's comparative boom (the EU's ius commune debates); the globalisation-and-harmonisation (the WTO-and-UNCITRAL regimes); the computational-and-empirical turn (the comparative law's data faces).