What happened to Southern Europe over the past few centuries? Between Greece and the Latin Countries, they had some of the greatest scientific minds and achievements, greatest civilizations, greatest philosophers, art, architecture, etc.

But ever since Rome fell it seems like they haven't really contributed much or led the way, and after colonialism ended they've been really irrelevant. And now they just seem like poorly run and aimless countries.

How/why was Northern Europe so much better at science/achievements beginning with Isaac Newton and through the present?