From The Sadness of Christ:
And as mad a part were it for a man to lose his soul
for the saving of his body, as if some frantic fool would rather have his body spilled280 than depart281
with his pilled cloak. For of the body in this wise speaketh Christ: ‘Is not the body more worth than
the garment? But mark you how highly he prizeth the soul: ‘Why, what art thou the better,’ saith he,
‘if thou shouldst win the whole world and sustain the loss of thy soul? Or what exchange will any man
make for his soul? And I say unto you my friends: Be not afraid of them that kill the body, and when
that is done are able to do no more. But I will tell you whom you ought to fear. Fear him that after he
hath killed the body hath power to cast it into the fire of hell beside. So I say unto you: Fear him.
Saint Thomas was giving up his life to save his soul.