I answer that, As stated above (Article [1]) state regards freedom or servitude. Now in spiritual things there is a twofold servitude and a twofold freedom: for there is the servitude of sin and the servitude of justice; and there is likewise a twofold freedom, from sin, and from justice, as appears from the words of the Apostle (Rm. 6:20,22), "When you were the servants of sin, you were free men to justice . . . but now being made free from sin," you are . . . "become servants to God."
Now the servitude of sin or justice consists in being inclined to evil by a habit of sin, or inclined to good by a habit of justice: and in like manner freedom from sin is not to be overcome by the inclination to sin, and freedom from justice is not to be held back from evil for the love of justice. Nevertheless, since man, by his natural reason, is inclined to justice, while sin is contrary to natural reason, it follows that freedom from sin is true freedom which is united to the servitude of justice, since they both incline man to that which is becoming to him. In like manner true servitude is the servitude of sin, which is connected with freedom from justice, because man is thereby hindered from attaining that which is proper to him. That a man become the servant of justice or sin results from his efforts, as the Apostle declares (Rm. 6:16): "To whom you yield yourselves servants to obey, his servants you are whom you obey, whether it be of sin unto death, or of obedience unto justice." Now in every human effort we can distinguish a beginning, a middle, and a term; and consequently the state of spiritual servitude and freedom is differentiated according to these things, namely, the beginning---to which pertains the state of beginners---the middle, to which pertains the state of the proficient---and the term, to which belongs the state of the perfect.