Excerpts from Supreme Master Ching Hai's Lecture:

Spirituality has two aspects: one is theory, and the other is practice. The theoretical aspect is what introduces us to God, Heaven, bliss, everlasting life and "seeing God while living." For example, it's just like I am doing now: introducing the apple. And the practical aspect of spirituality is the apple itself--it's when you eat it! ... That is, the things that we have been introduced to, we must know--we must taste... So in the beginning, when we first know God, He might appear to us as light; He might speak to us through human languages or as intuition in our mind. But later on, He will raise us higher and higher until we become one with Him. And that's when we can declare, "I and my Father are One," the way our Lord Jesus reached God...