A Toltec guide to personal freedom Don Miguel Ángel Ruiz (born 1952) is a Mexican author, shaman, and teacher. He was a surgeon until a near-death experience impelled him to seek answers in ancestral traditions of the Toltec in which his mother was a curandera (healer), and his grandfather a nagual (shaman) who, after death, continued to teach Ruiz in his dreams.

His most famous and influential work, The Four Agreements, was published in 1997 and has sold around 4 million copies. It advocates personal freedom from agreements and beliefs that we have made with ourselves and others that are creating limitation and unhappiness in our lives. Ultimately, it is about finding one's own integrity, self-love, and peace within this reality. The Four Agreements are:

Be Impeccable With Your Word. Speak with integrity. Say only what you mean. Avoid using the word to speak against yourself or to gossip about others. Use the power of your word in the direction of truth and love. Don’t Take Anything Personally. Nothing others do is because of you. What others say and do is a projection of their own reality, their own dream. When you are immune to the opinions and actions of others, you won’t be the victim of needless suffering. Don’t Make Assumptions. Find the courage to ask questions and to express what you really want. Communicate with others as clearly as you can to avoid misunderstandings, sadness and drama. With just this one agreement, you can completely transform your life. Always Do Your Best. Your best is going to change from moment to moment; it will be different when you are healthy as opposed to sick. Under any circumstance, simply do your best, and you will avoid self-judgment, self-abuse and regret.

Ruiz also wrote a workbook as a companion to The Four Agreements. He then wrote several other books, including The Voice of Knowledge, Prayers, and The Mastery of Love. In Beyond Fear, by Mary Carroll Nelson, he discusses some of his beliefs through a series of interviews, including his belief in the legend of Atlantis; his belief that the sun entered its sixth age on January 11, 1992, which should lead to a new age for humanity; and his belief in the spiritual power of the pyramid of the sun at Teotihuacan.

3 (audio)books I personally recommend are:
Don Miguel Ruiz - The Four Agreements
Don Miguel Ruiz - The Mastery Of Love
Don Miguel Ruiz - The Voice Of Knowledge