"tradition", viewed as central to Roman identity. There was no principle analogous to "separation of church and state". The priesthoods of the state religion were filled from the same social pool of men who held public office, and in the Imperial era, the Pontifex Maximus was the emperor. Roman religion was practical and contractual, based on the principle of do ut des, "I give that you might give." Religion depended on knowledge and the correct practice of prayer, ritual, and sacrifice, not on faith or dogma, although Latin literature preserves learned speculation on the nature of the divine and its relation to human affairs. For ordinary Romans, religion was a part of daily life. Each home had a household shrine at which prayers and libations to the family's domestic deities were offered. Neighbourhood shrines and sacred places such as springs and groves dotted the city. Apuleius (2nd century) described the everyday quality of religion in observing how people who passed a cult place might make a vow or a fruit offering, or merely sit for a while. The Roman calendar was structured around religious observances. In the Imperial era, as many as 135 days of the year were devoted to religious festivals and games (ludi). Women, slaves, and children all participated in a range of religious activities. In the wake of the Republic's collapse, state religion had adapted to support the new regime of the emperors. As the first Roman emperor, Augustus justified the novelty of one-man rule with a vast programme of religious revivalism and reform. Public vows formerly made for the security of the republic now were directed at the wellbeing of the emperor. So-called "emperor worship" expanded on a grand scale the traditional Roman veneration of the ancestral dead and of the Genius, the divine tutelary of every individual. Upon death, an emperor could be made a state divinity (divus) by vote of the Senate. Imperial cult, influenced by Hellenistic ruler cult, became one of the major ways Rome advertised its presence in the provinces and cultivated shared cultural identity and loyalty throughout the Empire. Cultural precedent in the Eastern provinces facilitated a rapid dissemination of Imperial cult, extending as far as the Augustan military settlement at Najran, in present-day Saudi Arabia. Rejection of the state religion became tantamount to treason against the emperor. This was the context for Rome's conflict with Christianity, which Romans variously regarded