It is claimed that occurrence of such a phenomenon dates from the early 18th century and stems from the Jewish tradition that the Divine Presence rests upon the Western Wall. There is however a dispute as to whether it is permissible according to Jewish law to insert slips of paper in to the crevices.[1] Some argue that the practice debases the holiness of the Wall and that the placement of notes should be discontinued.[1]
Over a million notes are placed each year in what has become a custom, not only for tourists, but also for high-profile dignitaries visiting Israel from abroad. The notes are collected twice a year and buried on the nearby Mount of Olives."