3 The deaf, again, and the dumb cannot always make a will, though here we are speaking not of persons merely hard of hearing, but of total deafness, and similarly by a dumb person is meant one totally dumb, and not one who merely speaks with difficulty; for it often happens that even men of culture and learning by some cause or other lose the faculties of speech and hearing. Hence relief has been afforded them by our constitution, which enables them, in certain cases and in certain modes therein specified, to make a will and other lawful dispositions. If a man, after making his will, becomes deaf or dumb through ill health or any other cause, it remains valid notwithstanding. 4 A blind man cannot make a will, except by observing the forms introduced by a law of our imperial father Justin. 5 A will made by a prisoner while in captivity with the enemy is invalid, even though he subsequently returns. One made, however, while he was in his own state is valid, if he returns, by the law of postliminium; if he dies in captivity it is valid by the lex Cornelia. TITLE XIII. OF THE DISINHERISON OF CHILDREN The law, however, is not completely satisfied by the observance of the rules hereinbefore explained. A testator who has a son in his power must take care either to institute him heir, or to specially disinherit him, for passing him over in silence avoids the will; and this rule is so strict, that even if the son die in the lifetime of the father no heir can take under the will, because of its original nullity. As regards daughters and other descendants of either sex by the male line, the ancients did not observe this rule in all its strictness; for if these persons were neither instituted nor disinherited, the will was not avoided, but they were entitled to come in with the instituted heirs, and to take a certain portion of the inheritance. And these persons the ascendant was not obliged to specially disinherit; he could disinherit them collectively by a general clause.