Dio Cassius 56.2-3 (speech of Augustus; tr. Earnest Cary):
[2.1] Though you are but few altogether, in comparison with the vast throng that inhabits this city, and are far less numerous than the others, who are unwilling to perform any of their duties, yet for this very reason I for my part praise you the more, and am heartily grateful to you because you have shown yourselves obedient and are helping to replenish the fatherland.  For it is by lives so conducted that Romans of later days will become a mighty multitude. We were at first a mere handful, you know, but when we had recourse to marriage and begot us children, we came to surpass all mankind not only in the manliness of our citizens but in the size of our population as well.  Bearing this in mind, we must console the mortal side of our nature with an endless succession of generations that shall be like the torch-bearers in a race, so that through one another we may render immortal the one side of our nature in which we fall short of divine bliss.  It was for this cause most of all that that first and greatest god, who fashioned us, divided the race of mortals in twain, making one half of it male and the other half female, and implanted in them love and compulsion to mutual intercourse, making their association fruitful, that by the young continually born he might in a way render even mortality immortal.  Indeed, even of the gods themselves some are accounted male and others female; and the tradition prevails that some have begotten others and some have been begotten of others. So even among those beings, who need no such device, marriage and the begetting of children have been approved as a noble thing.
[3.1] You have done right, therefore, to imitate the gods and right to emulate your fathers, so that, just as they begot you, you also may bring others into the world; that, just as you consider them and name them ancestors, others also may regard you and address you in similar fashion;  that the works which they nobly achieved and handed down to you with glory, you also may hand on to others; and that the possessions which they acquired and left to you, you also may leave to others sprung from your own loins.  For is there anything better than a wife who is chaste, domestic, a good house-keeper, a rearer of children; one to gladden you in health, to tend you in sickness; to be your partner in good fortune, to console you in misfortune; to restrain the mad passion of youth and to temper the unseasonable harshness of old age?  And is it not a delight to acknowledge a child who shows the endowments of both parents, to nurture and educate it, at once the physical and the spiritual image of yourself, so that in its growth another self lives again?  Is it not blessed, on departing from life, to leave behind as successor and heir to your blood and substance one that is your own, sprung from your own loins, and to have only the human part of you waste away, while you live in the child as your successor, so that you need not fall into the hands of aliens, as in war, nor perish utterly, as in a pestilence?  These, now, are the private advantages that accrue to those who marry and beget children; but for the State, for whose sake we ought to do many things that are even distasteful to us, how excellent and how necessary it is, if cities and peoples are to exist,  and if you are to rule others and all the world is to obey you, that there should be a multitude of men, to till the earth in time of peace, to make voyages, practise arts, and follow handicrafts, and, in time of war, to protect what we already have with all the greater zeal because of family ties and to replace those that fall by others.  Therefore, men,—for you alone may properly be called men,—and fathers,—for you are as worthy to hold this title as I myself,—I love you and praise you for this; and I not only bestow the prizes I have already offered but will distinguish you still further by other honours and offices, so that you may not only reap great benefits yourselves but may also leave them to your children undiminished.
Peter Michael Swan, The Augustan Succession:
An Historical Commentary on
Cassius Dio's Roman History
Books 55-56 (9 B.C.-A.D. 14)
(Oxford: Oxford University Press, 2004), p. 227:
Jörs observed over a century ago that in these speeches, first to husbands and
fathers, then to the unmarried, we have mainly Dio, not Augustus (Ehegesetze 53).4
4. Dio will have had an abundant didactic tradition on which to draw for such addresses. Advocacy of marriage and childrearing and denunciation of celibacy were commonplace in Greek and Roman writers on ethics
and politics; for a collection of texts see N. Geurts, Het huwelijk bij de Griekse en Romeinse moralisten (diss. Utrecht;
Amsterdam, 1928), 1–35, cf. 168–172 (German summary).