Insight is a prophetic capability unique to the Thin-blooded vampires. Individuals who demonstrate such abilities are called Seers but if a character lowers her generation through Diablerie she loses her insight.
Some vampires of the 14th and 15th Generations have an uncanny, well, insight into the plots and intrigues of elder vampires. They get strange hunches and prophetic dreams, blurt out names they should not know and sometimes even see waking visions of Gehenna.
However, it should be noted that Insight is not an All-Purpose Magic Answer Machine. Most of the time, Insight is vague, or the visions are obscure and symbolic. The more powerful the vampires involved, the less direct Insight will be. Even the most successful Insight only refers to Antediluvians through symbol and metaphor.
What's more, Insight reveals only information about plots and conflicts driven by vampires. This doesn't necessarily involve the lead-up to Gehenna... ate least not directly. The methuselahs and Antediluvians don't control every vampire, or even every elder. Most conflicts between vampires have no wider significance.
In rules terms, Insight is treated as a Background.
- Time of Thin Blood (book), p. 33, 74-76