Meaning What is night for all being, it is the time for an awakening to a self -controlled . And likewise, the time of awakening for all beings is night for resourceful yogi. ExplanationHere KRISHNA speaks about the opposite path that a realized soul takes,which is being aware that all the goods accumulated are merely temporary and  are perishable.  Everything shall be destroyed with the passing away of material body and does not last forever. You can run behind the worldly pleasures till you are breathing with life energy but as soon as the  the body leaves, everything becomes useless and perishable.  The wise seek the eternal bliss that is not perishable .He goes on with his self realization activities, undisturbed by material reactions. Eventually finding the real  and imperishable bliss and happiness. This is called a balanced and an equanimous soul .Night and day are one for a equanimous or a balanced yogi forever in a calm and composed state.