Pain. Joy. Information.
Knowledge was oddly enough the first element that seemed substantial to me as something in which you retain, even if it is given away.
I apologize in advance for being overly literal and analytical, as it stems from a lifelong fixation on all things lexicology and I just can't seem to help it :) Once I considered the word knowledge a bit deeper, I immediately changed it to the acute and direct, "Information." One's knowledge is something that is acquired throughout one's life, distinct to each beings personal collection of skills, education, experience, observation, understanding, and level or state of awareness, an exponential amount of factors would change the course of how knowledge itself could be given to another. Knowledge seems much too distinctly personal and environmentally morph able a property to do so. One's knowledge is owned only by them, even if they desire otherwise.
Of course you can pass on information of what you know and understand to another, to many others, and I can think of nothing better to be given in life, an insight to the knowledge of another. However, it is arguable that the knowledge obtained is all greatly modified by each person who receives the information. Without your experiences, your skills, awareness and understanding, it would be scientifically impossible for another being to ever acquire your knowledge, an acquired algorithm that is distinctive only to you and your life.
As for “Joy” and “Sorrow”... I hope they speak for themselves.
Take Care- Alex