It is not only the feelings and thoughts of others that are shared but their knowledge as well. So widely is knowledge shared that each spirit thinks he or she already knows what the next spirit knows, even if the first spirit had previously known nothing about the subject. Everything that others know about accordingly becomes common property. Some spirits retain the knowledge, some do not.
Spirits share these things with each other in conversation and through mental images accompanied by visual representations. The images that compose their thoughts also take visible form, you see, which allows everything to be presented in full detail. Spirits can depict more through a single mental image than they can express in a thousand words. Angels even perceive what lies behind the image, what feeling is connected with it, where that feeling comes from, what the purpose of it is, and many other inner aspects.
It is also common in the other world for one person to communicate pleasure and happiness in a remarkable way by actually passing them on to a number of others, who are as much affected by them as the original person. The communication takes place without any lessening of the feelings in the person who shares them to begin with.
I too was given the opportunity to share my pleasure with others by transferring it to them.
You can imagine, then, what kind of happiness exists in people who love their neighbor more than themselves and want nothing more than to spread their happiness to others. Their attitude traces its origin to the Lord, who communicates happiness to angels in the same way.
When people share happiness, they are constantly passing it along in the way just described, but they do so without reflecting on their active role in the process and without making a conscious, deliberate decision to engage in it.
from Secrets of Heaven, Sections 1390, 1391, 1392