But because the formula of fidelity or fealty ought herein above all else to be kept, there is language in the oath from which we can most conveniently learn a few of the acts which are not permitted. For a thing which is the opposite of something that is necessary is impossible, and by the same process of reasoning a thing which ought to be done is contradicted only by something that is not permitted. The formula of fealty, then, exacts the things which are inserted therein as being the necessary elements of loyalty, and expresses the latter by the words "sound," "safe," "honorable," "advantageous," "easy," "possible." If therefore, we are bound by fealty to anyone, we must not harm his soundness of body, or take from him the military resources upon which his safety depends, or presume to commit any act whereby his honor or advantage is diminished; neither is it lawful that that which is easy for him should be made difficult, or that which is possible impossible. Besides, one who holds a benefice from him whose liege man he is, owes to him aid and counsel in his undertakings; from which fact it is clearer than the sun how much is owed to the God of all, if so much is owed even to those to whom we are bound only by fealty.