Theses De legum interpretatione

LVII.
Care must also be taken to see whether the reason truly ceases altogether. For many things often occur in which the reason of the law is not so strong, yet it is not entirely absent. In this case, it should not be considered a sufficient cause, and therefore one should not be quick to depart from the general definition of the law simply because the reason is weaker.

LVIII.
For whenever the reason still holds in any part, the will of the law cannot fail entirely: and when the will of the law subsists, and is repugnant to restriction, this moderation made from the equitable and good cannot rightly be called such: since equity intends only to keep the will of the law valid and inviolate.

LIX.
With all these points thus executed and established, it seems opportune to finally report here: if this equity is reduced to writing, does it still retain the name of equity? In this matter, it must be held that equity still remains as long as it is described by those who lack the power to make law: otherwise, if he who can establish law ensures it is described with the intention that he wishes it to be observed and kept by all.

LX.
Then this interpretation loses the name of equity and assumes the name of law: and it begins, in turn, to need another interpretation, to which this very name of equity will likewise be rightly attributed.

LXI.
And if this also begins to obtain the force of law, it will require another equity: so that equity, converted into law, always provides the beginning and occasion for a new equity.

LXII.
In this way, although it is certain that jus Prætorium Praetorian law sprouted from the roots of equity, yet because that Praetorian equity was later described by Salvius Julianus, under the authority of the Divine Hadrian, and reduced into the form of that perpetual Edict, of Ulpian and others