Reply to Objection 3: The precepts forbidding concupiscence do not include the prohibition of first movements of concupiscence, that do not go farther than the bounds of sensuality. The direct object of their prohibition is the consent of the will, which is directed to deed or pleasure.
Reply to Objection 4: Murder in itself is an object not of concupiscence but of horror, since it has not in itself the aspect of good. On the other hand, adultery has the aspect of a certain kind of good, i.e. of something pleasurable, and theft has an aspect of good, i.e. of something useful: and good of its very nature has the aspect of something concupiscible. Hence the concupiscence of theft and adultery had to be forbidden by special precepts, but not the concupiscence of murder.