Taking refuge, now, becomes a very serious matter or serious practice, very fundamental, like the earth is used for many things, roads, houses, to grow food, crops, plants and so forth; the earth is used for so many things, for happiness.

Lama Zopa Rinpoche

These teachings on the nature of the mind and the stages of the path, including extensive teachings on refuge, were given by Lama Zopa Rinpoche at the Twenty-Eighth Kopan Meditation Course in November, 1995. You can read along with the transcript at https://www.lamayeshe.com/article/chapter/lecture-nine-nature-mind