Objection 1. It would seem that in the state of innocence man was passible. For "sensation is a kind of passion." But in the state of innocence man would have been sensitive. Therefore he would have been passible.
Objection 2. Further, sleep is a kind of passion. Now, man slept in the state of innocence, according to Genesis 2:21, "God cast a deep sleep upon Adam." Therefore he would have been passible.
Objection 3. Further, the same passage goes on to say that "He took a rib out of Adam." Therefore he was passible even to the degree of the cutting out of part of his body.
Objection 4. Further, man's body was soft. But a soft body is naturally passible as regards a hard body; therefore if a hard body had come in contact with the soft body of the first man, the latter would have suffered from the impact. Therefore the first man was passible.
On the contrary, Had man been passible, he would have been also corruptible, because, as the Philosopher says (Top. vi, 3): "Excessive suffering wastes the very substance."
I answer that, "Passion" may be taken in two senses.
First, in its proper sense, and thus a thing is said to suffer when changed from its natural disposition. For passion is the effect of action; and in nature contraries are mutually active or passive, according as one thing changes another from its natural disposition.
Secondly, "passion" can be taken in a general sense for any kind of change, even if belonging to the perfecting process of nature. Thus understanding and sensation are said to be passions. In this second sense, man was passible in the state of innocence, and was passive both in soul and body. In the first sense, man was impassible, both in soul and body, as he was likewise immortal; for he could curb his passion, as he could avoid death, so long as he refrained from sin.
Thus it is clear how to reply to the first two objections; since sensation and sleep do not remove from man his natural disposition, but are ordered to his natural welfare.
Reply to Objection 3. As already explained (92, 3, ad 2), the rib was in Adam as the principle of the human race, as the semen in man, who is a principle through generation. Hence as man does not suffer any natural deterioration by seminal issue; so neither did he through the separation of the rib.
Reply to Objection 4. Man's body in the state of innocence could be preserved from suffering injury from a hard body; partly by the use of his reason, whereby he could avoid what was harmful; and partly also by Divine Providence, so preserving him, that nothing of a harmful nature could come upon him unawares.
Source: Summa Theologica (New Advent)