But on the whole, we may with all due caution, in default of complete investigation of the question, assume that the Roman slaves were confined for the most part to the great and rich families, and were not used by them to any great extent in productive industry, but in supplying the luxurious needs of the household[333]. In all probability research will show that free labour was far more available than we are apt to think. We hear of no outbreak of feeling against slave labour, which might suggest a rivalry between the two. Slave labour, we may think, had filled a gap, created by abnormal circumstances, and did not oust free labour entirely; but it tended constantly to cramp it, and doubtless started notions of work in general which helped to degrade it[334]. Those immense _familiae urbanae_, of which the historian of slavery has given a detailed account in his second volume[335], belong rather to the early Empire than to the last years of the Republic--the evidence for them is drawn chiefly from Seneca, Juvenal, Tacitus, Martial, etc.; but such evidence as we have for the age of Cicero seems to suggest that the vast palaces of the capitalists, which Sallust describes as being almost like cities[336], were already beginning to be served by a familia urbana which rendered them almost independent of any aid from without by labour or purchase. Not only the ordinary domestic helpers of all kinds, but copyists, librarians, paedagogi as tutors for the children, and even doctors might all be found in such households in a servile condition, without reckoning the great numbers who seem to have been always available as escorts when the great man was travelling in Italy or in the provinces. Valerius Maximus tells us[337] that Cato the censor as proconsul of Spain took only three slaves with him, and that his descendant Cato of Utica during the Civil Wars had twelve; as both these men were extremely frugal, we can form an idea from this passage both of the increasing supply of slaves and of the far larger escorts which accompanied the ordinary wealthy traveller.