Nicely put, Wierd.
Synopsis:
According to the http://www.imperial-library.info/mwbooks/lessons.shtml#33, "Lie Rock" was one of Vivec's monstrous children from his coupling with Molag Bal. It was born from his "Second Aperture" (*cough*), and hid in the heavens, believing itself to be "born of golden wisdom and powers that should have forever been unalike," meaning that it was spawned in the moment that Vivec achieved CHIM. When Vivec sent Nerevar to find it, it hurled itself at Vivec City, and Vivec froze it in space above the High Fane. It is now the Ministry of Truth.
When Nerevar returned, he saw the frozen comet above his lord's city. He asked whether or not Vivec wanted it removed.
'I would have done so myself if I wanted, silly Hortator. I shall keep it there with its last intention intact, so that if the love of the people of this city for me ever disappear, so shall the power that holds back their destruction.'
Nerevar said, 'Love is under your will only.'
Lie Rock's impetus was frozen with it - when the magick that holds it in place disappears, it will collide with Vivec with the full force of a
Deep Impact asteroid. This is why the central message of the Loveletter is to "know love to avoid the Landfall".