Summa summae S. Thomae, Tomus II

You will ask 1° whether there is in man dominion with respect to himself and his operations.

I answer. affirmatively¹. Because, besides election, there is given in the will an active use. Therefore, besides the judgment directing election, there must be given another act in the intellect directing the use and execution, which is called dominion or command. The consequence is clear, because the will never operates without the direction of the intellect. The antecedent also holds, because election is concerned with the means in the order of intention, as it is future and the effect of the end. Active use is concerned with the same mean in the order of execution, as it is present and the efficient cause of the end had in reality. Therefore these two acts are concerned with formally distinct objects, although they are materially the same. — I subjoin. But acts are essentially distinguished according to formally distinct objects. Therefore. — Moreover, where there is a new and distinct difficulty, there is required a new and distinct act. But in execution a new, distinct, and far greater difficulty is found than in election, as is evident to all. For how many are there who choose easily and fail in execution!

You will ask 2° whether command is an act of reason or of will.

I answer. 1². Command is substantially an act of reason, presupposing an act of the will by whose power reason moves through command to the exercise of an act.

It is proved. To command says three things: first, to order him who is commanded to the doing of the work and to the means to be executed here and now for attaining the end; second, to intimate or declare the work to be done, not in the indicative mode, saying: « This is to be done, » as would be by a discriminative judgment, but in the imperative mode, saying: « Do this; » third, to move him or the power that is commanded to the execution of the work. But these three things belong to reason. 1° To order is to refer or compare one thing to another; which, since it is something intelligible, is proper to reason. 2° To intimate or declare is to make manifest and to speak; which also pertains to the intellect. 3° Although it belongs to the will per se primo to move, because it is the first mover to exercise, it nevertheless belongs secondarily and participatively to the intellect, from a preceding act of the will, because the virtue of the prior act remains in the following act: whence, as in election there remains something of the virtue of the preceding act of counsel, namely the order of the means, so in command there remains something of the virtue of election, namely the efficacy of moving.

Therefore command is an act of reason, presupposing an act of the will, by whose power reason moves through command to the exercise of an act.

You will ask 3° which acts are subject to the command of reason.

I answer.³ and let this be the general rule: Those acts which are in our power and arbitrement, and to which persuasive reason can move us, can be commanded; but those which are not in our power and arbitrement, and to which persuasive reason cannot move us, cannot be commanded. This rule is gathered from the very nature of command. For to command belongs to a superior governing and having the power to move and oblige so that he be obeyed; otherwise command would be vain.

From this general rule you will deduce which acts in particular are subject, or not subject, to the command of reason⁴.