The Senate was chiefly composed of men who belonged to an aristocracy by birth, and it admitted new men very unwillingly; a Marius with the power of the Army behind him could force his way into the Senate; a useful advocate like Cicero, or general like Pompeius, could be summoned to its ranks, but such men were unwelcome; they were accepted as a disagreeable necessity; all three learned at different times by bitter experience, that they were, at the best, tolerated.

An indication of the aristocratic nature of the Senate is afforded by the fact that Senators were forbidden to engage in trade, a prohibition which however they contrived to evade.

The school of writers which is interested in representing all forms of government, which have been successful as democratic, has done its best both in ancient and modern times to minimise the aristocratic character of the Roman Senate no less than its legislative supremacy; but the whole tone of Roman history is against them. A Roman Senator was distinctly a nobleman. Inside the Senate rank went by office; those Senators who had held the higher offices took precedence of others according to dignity of office; those families were most highly honoured who could show the greatest number of dignitaries among their ancestors, but the qualification of birth co-existed with rank, derived from office or a long ancestry of office holders. Long after the distinction between patrician and plebeian had ceased to have any meaning except in reference to certain priesthoods and religious ceremonies, the distinction between patrician and plebeian families was remembered, and occasionally reasserted itself practically; and it was some time before the official rank of Senator conferred by an Emperor was respected unless the recipient was entitled to Senatorial rank by descent. Among the few acts of the early Emperors which win the respect of contemporary historians, purgations of the Senate are included. Julius Cæsar tried to make the Senate a council of the Empire by enrolling in it non-Italians; but he was before his time, and his astute successor acted in a contrary spirit.

During all the constitutional changes of the last centuries of the Republic, the position of the Roman Senate remained unchanged in two particulars: it was the fountain head of Roman religion and of Roman law, and though the former might be held to be of transitory importance, the latter was undeniably permanent in its effects.

The Roman Senate did not alone make law, though it alone through the Prætors interpreted law. As a legislative body it shared its functions with the popular assemblies; its decrees were rather administrative than legislative, but it has never been rivalled, except, perhaps, by the English judges, in its power of expanding the application of existing laws and creating a legal system. This peculiarity of the Roman mind, its conservatism combined with a capacity for readjustment, gave us the Roman Empire; without it the Roman conquests would have gone for nothing. The Greek, far quicker witted than the Roman, was ready to change his laws at a moment’s notice. It was to him an open question whether his state should be democratic or oligarchic; the question could be settled according to convenience, by voting or by force; a new constitution could be framed to suit new emergencies. The Roman mind worked differently; with the Roman the new had, if possible, to be read into the old. The Roman did not become a constitution maker till he had passed under Greek influence, and he was remarkably unsuccessful in the task. He soon abandoned it, but he never failed in his casuistry; there was no conceivable adjustment of human relations which the Roman jurisconsult could not refer back to the Twelve Tables; he never troubled himself as to what was to the advantage of the greatest number, or as to the precise definition of justice; he simply took his law, his precedents, his authorised interpretations, and worked the new circumstances into line with the old forms.

Till the Greek influence modified Roman habits the education of the young Roman noblemen was largely legal; while the Greek youth was discussing morality speculatively, the Roman youth was being instructed in the application of law. He sat at the feet of some Mucius Scævola, and heard his solutions of knotty entanglements; the oratory in which he was trained was not the florid rhetoric, which may be addressed successfully to a mob, but forensic oratory addressed to trained intelligence.

With the legal temperament, the Roman combined the religious temperament, the habit of looking to authority rather than to speculation as a guide for his actions. The Sibylline books continued to be consulted in form, if not in fact, on occasions of emergency, long after the cultivated Roman had become familiar with the rationalistic speculations of the Greeks and the mathematicians.

The Senate might under these influences have easily degenerated into a futile subservience to stereotyped forms and habits which would have rendered expansion impossible; it might have opposed a Chinese rigidity to necessary innovations; but the destinies of Rome had ordained that from the beginning the principle of modification should exist alongside with a strong conservative tendency. It may be left to the antiquaries to decide exactly how much truth survives in the legends which form the chief part of early Roman history, but even if it were not demonstrable that the population of Rome was a composite population at a very early time, the fact would remain that the Romans themselves believed it to be composed of three elements: they believed that Latins, Sabines and Etruscans had been welded together under the Kings, and that the titular distinction between patrician and plebeian families survived from a further process of incorporation of aliens; thus there was ancient authority for innovation in such an important matter as the admission of new citizens. Athens was in this respect more conservative than Rome; the citizens of the most democratic state of the ancient world boasted of their pure native descent, while the conservative Roman found in his history a continuous process of immigration to the hills by the Tiber, repeated coalition, continued absorption.

While the Roman Senate was in one aspect a body of trained lawyers, in another it was a body of priests. The evolution of the priesthood as a separate profession is a comparatively modern process. In the history of Rome we see the first step in the process, the changes by which the men appointed to maintain the state religion or to conduct the ceremonial observances paid to particular gods became elected officials, after having been the representatives of certain families upon whom those obligations rested. The duties of religion which had previously been family duties became state duties; but this change did not relieve the Senate of its charge of the national religion. Just as the Senator was an expert in law, so he was an expert in ritual; he did not discuss questions of faith, but he decided points of ceremonial. Though the Colleges of Pontiffs and Augurs were not in the later days of the Republic necessarily drawn from the Senators, and though for a short period a restricted form of public election was applied to the former, practically the Senatorial families held these offices in their own hands, and the power which they thus wielded could only be taken from them by the expedient of combining in the person of the chief of the State the functions of chief Pontifex and chief Augur. Any public business could be suspended by the declaration of a Pontifex or Augur, that it was contrary to established ritual, or that the gods had by means of recognized signs and omens signified the occasion to be unfavourable.

The Senate was also an assembly of heads of families; when a Roman youth of Senatorial descent came of age, his father presented him to the Senate. Though inside his family the father was omnipotent, the Senate decided what actually was the family law; and in this respect the Senate dealt with the family, not with the individual. If the head of the family failed to rule his family properly, and thereby occasioned scandal, he might be marked by the Censor and degraded from his rank. In the family were included many persons whom we consider to be outside the family; slaves, freedmen and certain clients had rights as well as duties; the father of a family who contravened the regulations of the Senate in his relations with such persons caused a scandal, no less than in irregular relations with his wife or children. We are frequently surprised in reading the history of the early Emperors by the freedom with which they appeal to the Senate for commiseration in their private misfortunes, by their habit of assuming that the Senate is interested in their family affairs, but in this they were only acting as any other Senator would act. The point of view may be well illustrated from the procedure in divorce; divorce was a purely family affair with the Romans; a wife guilty of misconduct was divorced by her husband without any appeal to a law court. With ourselves a man is at liberty to apply for a divorce; if under certain circumstances he does not do so, we may admire his forbearance or despise his laxity, but there is no constituted authority which can force him to start an action; whereas a Roman Senator who permitted flagrantly scandalous conduct on the part of his wife could be, and sometimes was, degraded by the Censor, the good order of the State being imperilled by the irregularities in his family; cruelty to slaves or neglect of freedmen and clients were in the same way matters that came under the observation of the Senate, and of the Emperors as the leaders of the Senate.