Light Hope is perhaps better known as the guiding mentor to Etheria's greatest warrior She-Ra. Whenever she was in need or needed guidance, Light Hope was by She-Ra's side helping Etheria from finally falling to the hands of the Horde. 

Other than She-Ra, only Argo, king of the trolls knew about Light Hope and the Crystal Castle on Skydancer Mountain. Upon trying to locating Light Hope, Argo uttered the cryptic words:

'It is where you most want it to be, in plain sight, yet never seen. This is its nature.'

Whilst many know of the residence of Light Hope (the Crystal Castle), very few knew of its existence and only a handful of people knew about its keeper. No reason is given as to why it's location is kept secret other than it is keeping a power or knowledge in which needs to be kept away from Hordak.