The root-word buddh means to wake up, to know, to understand; and he or she who wakes up and understands is called a Buddha. It is as simple as that. The capacity to wake up, to understand, and to love is called Buddha nature. When Buddhists say "I take refuge in the Buddha," they are expressing trust in their own capacity of understanding, of becoming awake. The Chinese and Vietnamese say, "I go back and rely on the Buddha in me." Adding "in me" makes it clear that you yourself are the Buddha.
Thich Nhat Hanh (Buddhist monk, teacher, author, poet, and peace activist)