2. M.PorciusCatoLicinianus, a Roman jurist, the son of Cato the Censor by his first wife Licinia, and thence called Licinianus to distinguish him from his half-brother, M. Porcius Cato, the son of Salonia. His father paid great attention to his education, physical as well as mental, and studied to preserve his young mind from every immoral taint. He was taught to ride, to swim, to wrestle, to fence, and, perhaps to the injury of a weak constitution, was exposed to vicissitudes of cold and heat in order to harden his frame. The Censor would not allow his learned slave Chilo to superintend the education of his son, lest the boy should acquire slavish notions or habits, but wrote lessons of history for him in large letters with his own hand, and afterwards composed a kind of Encyclopaedia for his use. Under such tuition, the young Cato became a wise and virtuous man. He first entered life as a soldier, and served, B. C. 173, in Liguria under the consul M. Popilius Laenas. The legion to which he belonged having been disbanded, he took the military oath a second time, by the advice of his father, in order to qualify himself legally to fight against the enemy. (Cic. de Off. 1.11.) In B. C. 168, he fought against Perseus at Pydna under the consul Aemilius Paullus, whose daughter, Aemilia Tertia, he afterwards married. He distinguished himself in the battle by his personal prowess in a combat in which he first lost and finally recovered his sword. The details of this combat are related with variations by several authors. (Plut. Cat. Ma. 20; Justin, 23.2; V. Max. 3.12.16; Frontin. Strat. 4.5.17.) He returned to the troops on his own side covered with wounds, and was received with applause by the consul, who gave him his discharge in order that he might get cured. Here again his father seems to have cautioned him to take no further part in battle, as after his discharge he was no longer a soldier. (Plut. Quaest. Rom. 39.)

Henceforward he appears to have devoted himself to the practice of the law, in which he attained considerable eminence. In the obscure and corrupt fragment of Pomponius de Origine Juris (Dig. 1. tit. 2.38), after mentioning Sextus and Publius Aelius and Publius Atilius, the author proceeds to speak of the two Catos as follows : " Hos sectatus ad aliquid est Cato. Deinde M. Cato, princeps Porciae familiae, cujus et libri extant; sed plurimi filii ejus; ex quibus caeteri oriuntur." This passage seems to speak of a Cato before the Censor, but Pomponius wrote in paragraphs, devoting one to each succession of jurists, and the word Deinde commences that of the Catos, though the Censor had been mentioned by anticipation at the end of the preceding paragraph. From tlle Catos, father and son (ex quibus), the subsequent jurists traced their succession. Apollinaris Sulpicius, in that passage of Gellius (13.18) which is the principal authority with respect to the genealogy of the Cato family, speaks of the son as having written "egregios de juris disciplina libros." Festus (s. v. Mundus) cites the commlentarii juris civilis of Cato, probably the son, and Paullus (Dig. 45. tit. 1. s. 4.1) cites Cato's 15th book. Cicero (Cic. de Orat. 2.33) censures Cato and Brutus for introducing in their published responsa the names of the persons who consulted them. Celsus (Dig. 50. tit. 16. s. 98.1) cites an opinion of Cato concerning the intercalary month, and the regula or sententia Catoniana is frequently mentioned in the Digest. The regula Catoniana was a celebrated rule of Roman law to the effect, that a legacy should never be valid unless it would have been valid if the testator had died immediately after he had made his will. This rule (which had several exceptions) was a particular case of a more general maxim : " Quod initio non valet, id tract temporis non potest convalescere." The greater celebrity of the son as a jurist, and the language of the citations from Cato, render it likely that the son is the Cato of the Digest. From the manner in which Cato is mentioned in the Institutes (Inst. 1. tit. 11.12),--" Apud Catonem bene scriptum refert antiquitas,"--it may be inferred, that he was known only at second hand in the time of Justinian.

He died when pretor designatus, about B. C. 152, a few years before his father, who bore his loss with resignation, and, on the ground of poverty, gave him a frugal funeral. (Liv. Epit, 48; comp. Cic. de Senect. 19.)