The Catechism of the Summa - SECOND SECTION - A DETAILED SURVEY OF MAN'S RETURN TO GOD - XXIV. OF THE SINS OF SPEECH COMMITTED IN THE ORDINARY COURSE OF LIFE, VIZ., OF INVECTIVE, OF DETRACTION (AND CALUMNY), OF WHISPERINGS, OF MOCKERY, OF THE CURSE (E)

(E)  
What relation is there between the sin called the curse, and the four sins of invective, detraction, whispering, and mockery?

All these sins have in common this, that they are sins of the tongue which attack the good of our neighbour; but whereas the four latter do this by the words of a proposition which formulate evil, or deny the good of our neighbour, the curse attacks our neighbour's good by wishing him evil (LXXVI. 1, 4)
 
Is the curse then essentially bad?

Yes, whenever one wishes evil to another for evil's sake; and such a wish is, of itself, always a grave sin (LXXVI. 3).

Next - The Catechism of the Summa - SECOND SECTION - A DETAILED SURVEY OF MAN'S RETURN TO GOD - OF THE SINS THAT DECEIVE OUR NEIGHBOUR, AND OF THOSE THAT TAKE ADVANTAGE OF HIM, VIZ., OF FRAUD AND OF USURY (A)