So, according to Ra, the meaning of life is...

[JustLikeYou]

First, I'd like to underscore the fact that there is no joy without sorrow. One is warm and the other is cold, but both can be very subtle and both have deep lessons to offer.

Second, the term "Brothers and Sisters of Sorrow" was fairly well explained by Ra:

12.26
Imagine, if you will, the sands of your shores. As countless as the grains of sand are the sources of intelligent infinity. When a social memory complex has achieved its complete understanding of its desire, it may conclude that its desire is service to others with the distortion towards reaching their hand, figuratively, to any entities who call for aid. These entities whom you may call the Brothers and Sisters of Sorrow move towards this calling of sorrow. These entities are from all reaches of the infinite creation and are bound together by the desire to serve in this distortion.

14.18
The general cause of service such as the Confederation offers is that of the primal distortion of the Law of One, which is service. The One Being of the creation is like unto a body, if you will accept this third-density analogy. Would we ignore a pain in the leg? A bruise upon the skin? A cut which is festering? No. There is no ignoring a call. We, the entities of sorrow, choose as our service the attempt to heal the sorrow which we are calling analogous to the pains of a physical body complex distortion.

Imagine that the lifestyle you chose for yourself was as a medic in a third-world country, where disease and death are rampant and supplies are lacking. You have moved toward a great sorrow which called you. How do you escape feeling the sorrow of these people you came to heal, even if you are not the one who is diseased and dying? You can't. You feel their sorrow as your own.