St. Thomas on Justice - Article 1

Article 1. Whether justice is fittingly defined as being the perpetual and constant will to render to each one his right?

I answer that, The aforesaid definition of justice is fitting if understood aright. For since every virtue is a habit that is the principle of a good act, a virtue must needs be defined by means of the good act bearing on the matter proper to that virtue. Now the proper matter of justice consists of those things that belong to our intercourse with other men, as shall be shown further on (2). Hence the act of justice in relation to its proper matter and object is indicated in the words, "Rendering to each one his right," since, as Isidore says (Etym. x), "a man is said to be just because he respects the rights [jus] of others."
Now in order that an act bearing upon any matter whatever be virtuous, it requires to be voluntary, stable, and firm, because the Philosopher says (Ethic. ii, 4) that in order for an act to be virtuous it needs first of all to be done "knowingly," secondly to be done "by choice," and "for a due end," thirdly to be done "immovably." Now the first of these is included in the second, since "what is done through ignorance is involuntary" (Ethic. iii, 1). Hence the definition of justice mentions first the "will," in order to show that the act of justice must be voluntary; and mention is made afterwards of its "constancy" and "perpetuity" in order to indicate the firmness of the act.
Accordingly, this is a complete definition of justice; save that the act is mentioned instead of the habit, which takes its species from that act, because habit implies relation to act. And if anyone would reduce it to the proper form of a definition, he might say that "justice is a habit whereby a man renders to each one his due by a constant and perpetual will": and this is about the same definition as that given by the Philosopher (Ethic. v, 5) who says that "justice is a habit whereby a man is said to be capable of doing just actions in accordance with his choice."

 http://www.newadvent.org/summa/3058.htm#article1

Ave Maria!
Let's not be afraid to practice this powerful virtue but instead let us look to Our Lady and St. Joseph and ask them to help us.