Page "Caligula" Paragraph 49

Caligula's religious policy was a departure from that of his predecessors.

According to Cassius Dio, living Emperors could be worshipped as divine in the east and dead Emperors could be worshipped as divine in Rome.

Augustus had the public worship his spirit on occasion, but Dio describes this as an extreme act that emperors generally shied away from.

Caligula took things a step further and had those in Rome, including Senators, worship him as a physical living god.