During my third consulship I, Gaius Caesar, commissioned Sosigenes, an astronomer, to fix a new calendar to take effect at the end of the year, which would be extended by two intercalary months. The calendar was extended by ten days to give 365 except during leap years. Under my supervision Sosigenes added two days to January, December, and Sextilis (which, following the deification of my adopted son Gaius Octavius, later called Augustus, was called August). To April, June, September, and November were added one day. March, May, Quintilis (which, after my death and deification, was called July in honor of my birth month), February, and October all maintained their old lengths. The lengths of the months and the location of the leap day were not changed from my calendar by Pope Gregory--you use the same months as were set by Gaius Caesar in my third consulship