need justice and knowledge, as shown
above (A. 1, ad 1, 3; A. 2). But a judgment is not described as
unjust, if he who judges lacks the habit of justice or the knowledge
of the law. Neither therefore is it always unjust to judge by
usurpation, i.e. without authority.

_On the contrary,_ It is written (Rom. 14:4): "Who art thou that
judgest another man's servant?"

_I answer that,_ Since judgment should be pronounced according to the
written law, as stated above (A. 5), he that pronounces judgment,
interprets, in a way, the letter of the law, by applying it to some
particular case. Now since it belongs to the same authority to
interpret and to make a law, just as a law cannot be made save by
public authority, so neither can a judgment be pronounced except by
public authority, which extends over those who are subject to the
community. Wherefore even as it would be unjust for one man to force
another to observe a law that was not approved by public authority,
so too it is unjust, if a man compels another to submit to a judgment
that is pronounced by other than the public authority.

Reply Obj. 1: When the truth is declared there is no obligation to
accept it, and each one is free to receive it or not, as he wishes.
On the other hand judgment implies an obligation, wherefore it is
unjust for anyone to be judged by one who has no public authority.

Reply Obj. 2: Moses seems to have slain the Egyptian by authority
received as it were, by divine inspiration; this seems to follow from
Acts 7:24, 25, where it is said that "striking the Egyptian . . . he
thought that his brethren understood that God by his hand would save
Israel [Vulg.: 'them']." Or it may be replied that Moses slew the
Egyptian in order to defend the man who was unjustly attacked,
without himself exceeding the limits of a blameless defence.
Wherefore Ambrose says (De Offic. i, 36) that "whoever does not ward
off a blow from a fellow man when he can, is as much in fault as the
striker"; and he quotes the example of Moses. Again we may reply with
Augustine (QQ. Exod. qu. 2) [*Cf. Contra Faust. xxii, 70] that just
as "the soil gives proof of its fertility by producing useless herbs
before the useful seeds have grown, so this deed of Moses was sinful
although it gave a sign of great fertility," in so far, to wit, as it
was a sign of the power whereby he was to deliver his people.

With regard to Phinees the reply is that he did this out of zeal for
God by Divi