At one time, there were detailed contemporaneous histories on Caligula, but they are now lost. Additionally, the historians who wrote them are described as biased, either overly critical or praising of Caligula. Nonetheless, these lost primary sources, along with the works of Seneca and Philo, were the basis of surviving secondary and tertiary histories on Caligula written by the next generations of historians. A few of the contemporaneous historians are known by name. Fabius Rusticus and Cluvius Rufus both wrote condemning histories on Caligula that are now lost. Fabius Rusticus was a friend of Seneca who was known for historical embellishment and misrepresentation. Cluvius Rufus was a senator involved in the assassination of Caligula.