Obj. 3:  Further, in fear, the heat is withdrawn from the outer to the inner parts of the body.  If, therefore, man trembles in his outward parts, through the heat being withdrawn thus; it seems that fear should cause this trembling in all the external members.  But such is not the case.  Therefore trembling of the body is not caused by fear.

On the contrary, Cicero says (De Quaest.  Tusc. iv, 8) that “fear is followed by trembling, pallor and chattering of the teeth.”

I answer that, As stated above (A. 1), in fear there takes place a certain contraction from the outward to the inner parts of the body, the result being that the outer parts become cold; and for this reason trembling is occasioned in these parts, being caused by a lack of power in controlling the members:  which lack of power is due to the want of heat, which is the instrument whereby the soul moves those members, as stated in De Anima ii, 4.

Reply Obj. 1:  When the heat withdraws from the outer to the inner parts, the inward heat increases, especially in the inferior or nutritive parts.  Consequently the humid element being spent, thirst ensues; sometimes indeed the result is a loosening of the bowels, and urinary or even seminal evacuation.  Or else such like evacuations are due to contraction of the abdomen and testicles, as the Philosopher says (De Problem. xxii, 11).

This suffices for the Reply to the Second Objection.

Reply Obj. 3:  In fear, heat abandons the heart, with a downward movement:  hence in those who are afraid the heart especially trembles, as also those members which are connected with the breast where the heart resides.  Hence those who fear tremble especially in their speech, on account of the tracheal artery being near the heart.  The lower lip, too, and the lower jaw tremble, through their connection with the heart; which explains the chattering of the teeth.  For the same reason the arms and hands tremble.  Or else because the aforesaid members are more mobile.  For which reason the knees tremble in those who are afraid, according to Isa. 35:3:  “Strengthen ye the feeble hands, and confirm the trembling [Vulg.:  ‘weak’] knees.” ________________________

FOURTH ARTICLE [I-II, Q. 44, Art. 4]

Whether Fear Hinders Action?

Objection 1:  It would seem that fear hinders action.  For action is hindered chiefly by a disturbance in the reason, which directs action.  But fear disturbs reason, as stated above (A. 2).  Therefore fear hinders action.

Obj. 2:  Further, those who fear while doing anything, are more apt to fail:  thus a man who walks on a plank placed aloft, easily falls through fear; whereas, if he were to walk on the same plank down below, he would not fall, through not being afraid.  Therefore fear hinders action.

Obj. 3:  Further, laziness or sloth is a kind of fear.  But laziness hinders action.  Therefore fear does too.