He adduces a number of illustrations to show that reason alone is

insufficient to make a moral sentiment
He adduces a number of illustrations to show that reason alone is
insufficient to make a moral sentiment. He bids us examine Ingratitude,
for instance; good offices bestowed on one side, ill-will on the other.
Reason might say, whether a certain action, say the gift of money, or
an act of patronage, was for the good of the party receiving it, and
whether the circumstances of the gift indicated a good intention on the
part of the giver; it might also say, whether the actions of the person
obliged were intentionally or consciously hurtful or wanting in esteem
to the person obliging. But when all this is made out by reason, there
remains the sentiment of abhorrence, whose foundations must be in the
emotional part of our nature, in our delight in manifested goodness,
and our abhorrence of the opposite.