Objection 1. It would seem that six species of fear are unsuitably assigned by Damascene (De Fide Orth. ii, 15); namely, "laziness, shamefacedness, shame, amazement, stupor, and anxiety." Because, as the Philosopher says (Rhet. ii, 5), "fear regards a saddening evil." Therefore the species of fear should correspond to the species of sorrow. Now there are four species of sorrow, as stated above (Question 35, Article 8). Therefore there should only be four species of fear corresponding to them.
Objection 2. Further, that which consists in an action of our own is in our power. But fear regards an evil that surpasses our power, as stated above (Article 2). Therefore laziness, shamefacedness, and shame, which regard our own actions, should not be reckoned as species of fear.
Objection 3. Further, fear is of the future, as stated above (Question 1, Article 2). But "shame regards a disgraceful deed already done," as Gregory of Nyssa [Nemesius, De Nat. Hom. xx.] says. Therefore shame is not a species of fear.
Objection 4. Further, fear is only of evil. But amazement and stupor regard great and unwonted things, whether good or evil. Therefore amazement and stupor are not species of fear.
Objection 5. Further, Philosophers have been led by amazement to seek the truth, as stated in the beginning of Metaphysics. But fear leads to flight rather than to search. Therefore amazement is not a species of fear.
On the contrary suffices the authority of Damascene and Gregory of Nyssa [Nemesius] (Cf. Objection 1,3).
I answer that, As stated above (Article 2), fear regards a future evil which surpasses the power of him that fears, so that it is irresistible. Now man's evil, like his good, may be considered either in his action or in external things. In his action he has a twofold evil to fear. First, there is the toil that burdens his nature: and hence arises "laziness," as when a man shrinks from work for fear of too much toil. Secondly, there is the disgrace which damages him in the opinion of others. And thus, if disgrace is feared in a deed that is yet to be done, there is "shamefacedness"; if, however, it be a deed already done, there is "shame."
On the other hand, the evil that consists in external things may surpass man's faculty of resistance in three ways. First by reason of its magnitude; when, that is to say, a man considers some great evil the outcome of which he is unable to gauge: and then there is "amazement." Secondly, by reason of its being unwonted; because, to wit, some unwonted evil arises before us, and on that account is great in our estimation: and then there is "stupor," which is caused by the representation of something unwonted. Thirdly, by reason of its being unforeseen: thus future misfortunes are feared, and fear of this kind is called "anxiety."
Reply to Objection 1. Those species of sorrow given above are not derived from the diversity of objects, but from the diversity of effects, and for certain special reasons. Consequently there is no need for those species of sorrow to correspond with these species of fear, which are derived from the proper division of the object of fear itself.
Reply to Objection 2. A deed considered as being actually done, is in the power of the doer. But it is possible to take into consideration something connected with the deed, and surpassing the faculty of the doer, for which reason he shrinks from the deed. It is in this sense that laziness, shamefacedness, and shame are reckoned as species of fear.
Reply to Objection 3. The past deed may be the occasion of fear of future reproach or disgrace: and in this sense shame is a species of fear.
Reply to Objection 4. Not every amazement and stupor are species of fear, but that amazement which is caused by a great evil, and that stupor which arises from an unwonted evil. Or else we may say that, just as laziness shrinks from the toil of external work, so amazement and stupor shrink from the difficulty of considering a great and unwonted thing, whether good or evil: so that amazement and stupor stand in relation to the act of the intellect, as laziness does to external work.
Reply to Objection 5. He who is amazed shrinks at present from forming a judgment of that which amazes him, fearing to fall short of the truth, but inquires afterwards: whereas he who is overcome by stupor fears both to judge at present, and to inquire afterwards. Wherefore amazement is a beginning of philosophical research: whereas stupor is a hindrance thereto.
Source: Summa Theologica (New Advent)