Eo modo quo potentiae animae se habent ad hoc quod obediant rationi, hoc modo se habent etiam corporis membra, quia membra corporis sunt organa quaedam potentiarum animae.
In the same way that the powers of the soul stand in respect of obedience to formal aspect, so do the members of the body stand in respect thereof, because the members of the body are organs of the soul's powers.
Quia igitur vires sensitivae subduntur imperio rationis, non autem vires naturales; ideo omnes motus membrorum quae moventur a potentiis sensitivis, subduntur imperio rationis; motus autem membrorum qui consequuntur vires naturales, non subduntur imperio rationis.
Since then the sensitive powers are subject to the command of formal aspect, whereas the natural powers are not; therefore all movements of members, that are moved by the sensitive powers, are subject to the command of formal aspect; whereas those movements of members, that arise from the natural powers, are not subject to the command of formal aspect.
Augustinus dicit, VIII Confess., "imperat animus ut moveatur manus, et tanta est facilitas, ut vix a servitio discernatur imperium".
Augustine says (Confess. viii, 9): "The mind commands a movement of the hand, and so ready is the hand to obey, that scarcely can one discern obedience from command."
Membra non movent seipsa, sed moventur per potentias animae; quarum quaedam sunt rationi viciniores quam vires animae vegetabilis.
The members do not move themselves, but are moved through the powers of the soul; of which powers, some are in closer contact with the formal aspect than are the powers of the vegetal soul.
Sicut Augustinus dicit in XIV de Civ. Dei, hoc quod motus genitalium membrorum rationi non obedit, est ex poena peccati, ut scilicet anima suae inobedientiae ad Deum in illo praecipue membro poenam inobedientiae patiatur, per quod peccatum originale ad posteros traducitur.
As Augustine says (De Civ. Dei xiv, 17,20) it is in punishment of sin that the movement of these members does not obey formal aspect in this sense, that the soul is punished for its rebellion against God, by the insubmission of that member whereby original sin is transmitted to posterity.
Sed quia per peccatum primi parentis, ut infra dicetur, natura est sibi relicta, subtracto supernaturali dono quod homini divinitus erat collatum; ideo consideranda est ratio naturalis quare motus huiusmodi membrorum specialiter rationi non obedit.
But because, as we shall state later on, the effect of the sin of our first parent was that his nature was left to itself, through the withdrawal of the supernatural gift which God had bestowed on man, we must consider the natural aspect of this particular member's insubmission to formal aspect.
Cuius causam assignat Aristoteles in libro de causis motus animalium, dicens involuntarios esse motus cordis et membri pudendi, quia scilicet ex aliqua apprehensione huiusmodi membra commoventur: inquantum scilicet intellectus et phantasia repraesentant aliqua ex quibus consequuntur passiones animae, ad quas consequitur motus horum membrorum. Non tamen moventur secundum iussum rationis aut intellectus, quia scilicet ad motum horum membrorum requiritur aliqua alteratio naturalis (scilicet caliditatis et frigiditatis), quae quidem alteratio non subiacet imperio rationis.
This is stated by Aristotle (De Causis Mot. Animal.) who says that "the movements of the heart and of the organs of generation are involuntary," because these members are stirred at the occasion of some apprehension: insofar as the intellect and imagination represent such things as arouse the passions of the soul, of which passions the movements of these members are a consequence. But they are not moved at the command of formal aspect or intellect, because these movements are conditioned by a certain natural change (e.g., of heat and cold), which change is not subject to the command of formal aspect.
Specialiter autem hoc accidit in his duobus membris, quia utrumque istorum membrorum est quasi quoddam animal separatum, inquantum est principium vitae; principium autem est virtute totum. Cor enim principium est sensuum, et ex membro genitali virtus exit seminalis, quae est virtute totum animal. Et ideo habent proprios motus naturaliter: quia principia oportet esse naturalia.
This is the case with these two organs in particular, because each is as it were a separate animal being, insofar as it is a principle of life; and the principle is virtually the whole. For the heart is the principle of the senses; and from the organ of generation proceeds the seminal virtue, which is virtually the entire animal. Consequently they have their proper movements naturally: because principles must needs be natural.
In his quae ad intellectum et voluntatem pertinent, primum invenitur id quod est secundum naturam, ex quo alia derivantur: ut a cognitione principiorum naturaliter notorum, cognitio conclusionum; et a voluntate finis naturaliter desiderati, derivatur electio eorum quae sunt ad finem. Ita etiam in corporalibus motibus principium est secundum naturam.
In things pertaining to intellect and will, that which is according to nature stands first, whence all other things are derived: thus from the knowledge of principles that are naturally known, is derived knowledge of the conclusions; and from volition of the end naturally desired, is derived the choice of the means. So also in bodily movements the principle is according to nature.