Many Masters have said: "Urge on the horse of awareness with the whip of presence!" And, in fact, if awareness is not quickened by presence it cannot function.
Let's examine an example of awareness: suppose that in front of a person in a normal condition there is a cup full of poison, and that person is aware of what it is. Adult and balanced persons, knowing the poison for what it is and aware of the consequences of taking it, do not need much clarification about it. But they have to warn those who don't know about the poison being there, by saying something like: "In this cup there is some poison, and it's deadly if swallowed!" Thus, by creating awareness in others, the danger can be avoided. This is what we mean by awareness. […]
Now we can continue the metaphor of the poison to show what we mean by presence. If the person who has a cup of poison in front of them, even though they are aware and know very well what the consequences of taking the poison would be, does not have a continuous presence of attention to the fact that the cup contains poison, it may happen that they become distracted and swallow some of it. So if awareness is not continually accompanied by presence it is difficult for there to be the right results. This is what we mean by presence. […]
In truth, if one does not have awareness inseparably linked to presence, there absolutely cannot arise a really genuine compassion. As long as one does not have the real experience of being moved by compassion for others, it is useless to pretend that one is so very full of compassion. There is a Tibetan proverb about this, which says: "Even if you've got eyes to see other people, you need a mirror to see yourself!" As this proverb implies, if one really wants a genuine compassion for others to arise in oneself, it is necessary to observe one's own defects, be aware of them, and mentally put yourself in other people's places to really discover what those persons' actual conditions might be. The only way to succeed in this is to have the presence of awareness. Otherwise, even if one pretends to have great compassion, a situation will sooner or later arise which shows that compassion has never really been born in us at all.
Until a pure compassion does arise, there is no way to overcome one's limits and barriers.
--Namkhai Norbu Rinpoche