414. With comparatives and words implying comparison the ablative is used to denote the Degree of Difference.
Quīnque mīlibus passuum distat.
It is five miles distant.
ā mīlibus passuum circiter duōbus (B. G. 5.32)
at a distance of about two miles.
(For ā as an adverb, see § 433.3)
aliquot ante annīs (Tusc. 1.4)
several years before
Aliquantō post suspexit. (Rep. 6.9)
A while after, he looked up.
multō mē vigilāre ācrius (Cat. 1.8)
that I watch much more sharply
Nihilō erat ipse Cyclōps quam ariēs prūdentior
The Cyclops himself was not a bit wiser than the ram.
a. The ablatives quō . . . eō (hōc), and quantō . . . tantō, are used correlatively with comparatives, like the English the . . .the.1
quō minus cupiditātis, eō plūs auctōritātis (Liv. 24.28)
the less greed, the more weight
(by what the less, by that the more)
Quantō erat gravior oppūgnātiō, tantō crēbriōrēs litterae mittēbantur. (B. G. 5.45)
The more severe the siege was, the more frequently letters were sent.
Note— To this construction are doubtless to be referred all cases of quō and eō (hōc) with a comparative, even when they have ceased to be distinctly felt as degree of difference and approach the Ablative of Cause.
eōque mē minus paenitet, etc. (N. D. 1.8)
and for that reason I regret less, etc. (by so much the less I regret)
Haec eō facilius faciēbant, quod, etc. (B. G. 3.12)
This they did the more easily for this reason, because, etc.
cf. hōc mâiōre spē, quod, etc. (id. 3.9)
b. The Ablative of Comparison (§ 406) and the Ablative of Degree of Difference are sometimes used together with the same adjective.
paulō minus ducentīs (B. C. 3.28)
a little less than two hundred
patria, quae mihi vītā meā multō est cārior (Cat. 1.27)
my country, which is much dearer to me than life
But the construction with quam is more common.