In La ciudad indiana, a classic on colonial Buenos Aires read by many generations, Juan Agustín García says that slaves were introduced into the colonial estancia because they were cheaper than peons. By investing a few hundred pesos on a slave who would work 15 to 20 years, he argues, estancieros could save thousands in peons' salaries. As a result peons could not easily find jobs, and when they did find one, monthly wages of 6 to 8 pesos were sufficient to cover only “their most pressing needs.” All estancias, however, were “full of gauchos with no regular wage because rich men, instead of hiring all the peons they need, keep on only foremen and slaves.” How was it, then, that these gauchos without a regular salary did not offer to work for under 6 pesos a month? If they had done so, why should landowners still invest in slaves? If they did not do so, why did slaves not take the place of peons completely? García does not answer these questions. The idea prevailing in his writing is that free labor was unstable, so slaves had to be introduced into rural work to compensate for that instability, due in turn to the peons' lack of industriousness. More recent contributions have also singled out the unstable nature of free labor as the reason for the increasing use of slaves in rural work in late-eighteenth-century Buenos Aires. Free labor was unstable, it has been argued, because of a subsistence sector to which peons could turn after taking on casual work simply to earn money for those needs that could not be satisfied in that sector.