We continue:
in toto orbe terrarum vix credas quemquam esse minus deditum rebus novis et arcanis, quod ineptias tales omnino spernebant.
In all the globe of lands you would scarcely believe anyone to be less given to new and arcane things, because stupidities of those kinds they just despised.
In toto orbe terrarum is a common Latin phrase. A solid English equivalent would be “in the whole wide world.” Think of spernebat as they spurned. Credas is obviously connected to credibility and credit (would you credit it?). Minus in Latin means less, as it still does in simple arithmetic. Eight minus four means eight less four.
Deditum, the Latin for given, is related to our dedicate. If you are given to something you are dedicated to enjoying it.