 Some spirits communicate with the living in their dreams, such as Horace Goodspeed and Boone Carlyle, who each appear to John Locke on separate occasions.Walt has made appearances on the Island in places he could not have been (most notably to Shannon Rutherford in early episodes of season 2 and to John Locke in season 3); since Jacob's brother is unable to take on the form of the living, and since Walt isn't dead, the origin of this vision is unclear, although it may be related to Walt's special powers, which have been hinted at but never fully explained.Also, while Jacob's spirit was on the Island, Jacob as a child appeared before Hurley and physically took a bag from Hurley's hand, thus showing that he was actually physically present, and not just a spirit.