This discourse, taught by the Rebbe in 1965 and edited in 1990, concerns the nature of Holiness.  One aspect is expressed by the individual reaching upwards to the Divine; but there are two ways in which the Divine responds, one concerning inwardness, Torah study, and the other on a more practical level, expressed by observing the Mitzvot.  These three modes are depicted by the words ‘Holy, holy, holy’ in the daily prayers.