“The mind of one Buddha is the mind of all Buddhas,” said learned teacher Gelek Rimpoche, in a commentary on Vajrayogini.  “The mind of all Buddhas is the mind of a Buddha. It is like a huge space-like pool of total knowledge, total enlightenment.”
In his commentary, Gelek Rimpoche* explained that “The Buddha doesn’t mean just one Buddha, Buddha means all the enlightened ones.” This concept is reinforced in various Sutras, such as the Avatamsaka Sutra: “All Buddhas are One Buddha.”  This does not mean that all Buddhas and enlightened deities are identical in the conventional sense but ultimately, their essence is the same.
Without getting into a long discussion on Advaya (non duality), the important concept is that Buddhas — who are free from conventional reality — can be thought of as both individuals (in the conventional sense, for the purposes of specialized meditation practices) or as non dual One (for the purposes of understanding Jewel Collection Refuge.) Even putting aside the notion of conventional/ultimate truth, most practices contain a visualization where we “merge” all Buddhas in our meditations (symbolically as light) into one, and then, finally, into our teacher and, often, into ourselves.
The notion that the practice of one enlightened being can merge the practice of all enlightened beings could be reassuring to the advanced practitioner, or someone who over the years has collected many teachings and practices. Gelek Rimpoche explains: “That is why you don’t have to think, ‘Yeah, I have Lama Vajrayogini here, but I have forgotten Shakyamuni, I forgot the Medicine Buddha, I forgot Tara there. What has happened to my refuge?”
H.E. Zasep Tulku Rinpoche, in an interview with Buddha Weekly, gave this context: “They are the same deities. For example, Manjushri is a Kriya Tantra, a lower Tantra deity. But Manjushri is the same as Yamantaka. No difference. Yamantaka is Higher Tantra. Tara is the Lower Tantra practice. But you have a Higher Tantra practice called Chittimani Tara. Then, we also have Vajrayogini, which is also an emanation of Tara.”
Why Are There Many Yidams: Visualized Forms of Enlightenment, Symbols of Ultimate Yidam?
This concept begs the question, why then do we have so many Yidams? “There are many yidams with different forms – peaceful and wrathful pure forms of being, alone, or in union with their consorts,” wrote His Eminence Jamgon Kongtrul Rinpoche the Third.
“Why are there so many? Yidams are visualized pure forms that manifest from dharmadhatu’s empty essence as the lucid self-display of our Lama’s compassion.” The goal of Yidam practice is critical to understanding these forms: ” What is the purpose of Vajrayana practice? Purifying one’s impure perception of all appearances and experiences.”
He continued: “I mentioned that students have different mental capacities, views, and goals; they have different hopes and fears. Yidams are images for the benefit of students’ varying propensities. One leads one’s life in reliance on a vast variety of concepts. Therefore one needs a reference-point in practice, too, a reference-point that accords with one’s personal inclinations. Students aren’t ready to focus their attention on the ultimate yidam and consequently need pure representations.”
Yidams arise from “Lama’s compassion.” His Eminence emphasized the form is not real at the ultimate level: “Are the many yidams we see in pictures and visualize real? No, they are symbols of the ultimate yidam. The various forms and attributes of the deities point to manifold habits of clinging, grasping, and holding impure appearances in one’s mind. There are so many impure ideas and things one thinks are real. Each yidam symbolizes one of the many aspects of clinging and clutching. One needs to know this.”
He illustrated with the famous story of Marpa and Naropa: “When Naropa transmitted the Hevajra initiation to Marpa, Hevajra appeared in space before Marpa. Naropa asked him, “Who do you venerate?” Marpa pondered, “I can always meet my Lama, but the yidam is exceptional.” He prostrated to the yidam and only then understood that he had erred; he then realized that the yidam was the display of his Lama’s mind. The moment he understood this, Hevajra merged with Naropa.”
“Jewel Collection Refuge”: Not an Invitation for Laziness, But Reassuring for Students Struggling with Multiple Commitments
Typically, advanced students in Vajrayana, for example, attend many teachings, often with many teachers. If those teachings include empowerment, they can come with a stated (or not stated) commitment to practice. After all, what’s the use of a teaching without the practice? By the time students reach the higher tantric yogas, they might have a dozen practices — a virtually impossible commitment in today’s world of lay practitioners. Ten empowerments over ten years could involve ten hours a day of practice. For this reason, many teachers, in various commentaries, particularly on Higher Yogic practices, have emphasized this point.
Early in my practice, I remember thinking, “How do these great teachers who have literally dozens of empowerments from multiple teachers manage all those practice commitments?” The answer, in part, is “Jewel Collection Refuge,” which has always been a part of all practices. For example, when a student visualizes all the Buddhas and enlightened beings dissolving into the Yidam or Guru, this is basically — at least in part — a mental visualization of “Jewel Collection Refuge.”
“This system is called ‘jewel collection refuge’,” explained Gelek Rimpoche in the Vajrayogini commentary. “This is what we call the jewel collection system: one object representing everybody.”
This way, when you practice your chosen Yidam, you are in effect practices all the Buddhas, including other enlightened deities for which you might have commitments. It also means that a student can regularly attend teachings on other practices (if they have the appropriate empowerment or training) without conflicting with their main practice.
Renewing Samaya — Another Reason to “Collect” Empowerments
Jewel Collection Refuge also frees a student to attend empowerments given by their teacher that might not be their main Yidam. The main reason a student might wish to do this is to renew “samaya” or the vow or bond with the teacher — thereby purifying us of the break.
During the course of time, we might have missed practice obligations, or broken a minor vow. For a student with Higher Yoga Tantra initiations the vows are serious and extensive. The two main ways to renew the bond are self initiation — if the student has completed the appropriate counting retreat followed by Fire Puja — or initiation from the teacher. However, the teacher may not offer the empowerment in your personal Yidam every year; the concept of Jewel Collection Refuge frees us to attend empowerments with our teacher in other practices, while retaining our main Yidam — allowing us to also renew samaya.
Normally, the empowerments involved would be of the same class. For example, if I have a Yidam of the Action Tantra type, another Kriya Tantra initiation might renew fully the samaya. If I have a Mana Annut (Highest Yoga) Tantra initiation, I would probably need another Higher Yoga practice empowerment to fully renew samaya, although any renewal of vows with one’s teacher is beneficial.
Changing Yidams: Is it Okay to Change?
Even though most Yidam practices come with commitments to practice, from time to time, students might change Yidams on a teacher’s advice, or due to their own specific needs. A student who is overly attached to “desire” and attachment might choose Vajrayogini. Another, subject to ferocious and uncontrollable anger might choose Yamantaka. A student who feels vulnerable and unprotected might feel comfort with Green Tara practice. Someone who lacks compassion might benefit from Avalokiteshvara practice. Someone focusing on an illness might choose Medicine Buddha or Black Manjushri. In essence, at the ultimate level, they are they same Yidam, conventionally, the appear separate. The practice and visualization changes, helping to illustrate that all things are ultimately empty — but also helping us to focus on our specific “weakness” or attachments.
Zasep Tulku Rinpoche gave this guidance: “You need to have this strong internal connection. You feel this strong connection to, say, Yamantaka. You feel an attraction. You feel an urge. It’s hard to put into words, but it’s sort of like “chemistry.” Just like people are attracted to certain people, there’s a chemistry. You feel something unusual. It’s like when you find your “soul mate.” In Tantra, we call this “Yidam” which means “heart bond deity.” You have to have the heart bond connection.” 
Why Are Yidams a Powerful Meditation?
His Eminence Jamgon Kongtrul Rinpoche the Third explains: “It is a fact that we cling to self-importance and believe we have a self-existing identity. Should someone tell us we don’t really exist, it would be quite strange and difficult to accept. This is the reason why the creation stage of practice is special. No words are lost arguing whether one exists or not, but a practitioner directly imagines his or her body in the form of a yidam, a practice that helps diminish and eventually eliminate clinging to a self. This can only take place if one knows what a yidam really is. Yidams are expressions of complete purity. If one is aware of this fact and visualizes oneself as a yidam, clinging to a self automatically and naturally diminishes, eventually ceases, and never arises again.”
A Key Reason for Yidam Practice: Helping Us Understand Correct View
Most advanced Yidam practices, contain “creation stage” meditation — often progressing into “completion stage meditation.” For this reason, one complete practice is all that’s needed — completed well, and with the understanding that all Yidams are ultimately the same nature.
His Eminence Jamgon Kongtrul Rinpoche explains it this way: “What is the correct view? Knowing that relative appearances and their ultimate reality are inseparable and not contradictory. What does the correct view have to do with the yidams? “Relative” refers to the way we apprehend, the reason we visualize yidams. “Ultimate” refers to the true nature of all appearances and experiences, the fact that all things are empty, i.e., devoid of inherent existence — the reason we meditate on the completion stage of each practice. Both creation and completion practices — relative and ultimate — coexist. By engaging in the techniques of yidam meditation correctly, general and specific accomplishments are achieved.
“To avoid falling into the extreme view and believing nothing exists, that all things are merely empty, the creation stage of meditation practice is carried out. To avoid falling into the extreme view and believing phenomena exist permanently, the completion stage of meditation practice is practiced. Realizing the indivisibility of both stages of practice enables us to experience that everything is co-emergent bliss and emptiness, the purpose of Vajrayana. If one practices correctly, one will attain accomplishments.”
*Gelek Rimpoche spells Rimpoche with an “m”. Some Rinpoche’s spell (more commonly) with an “n”. Out of respect we’re using the M spelling.
 “Vajrayogini Extensive Commentary” Gelek Rimpoche, Jewel Heart.
 “Part 3: Zasep Tulku Rinpoche discusses how to find a teacher; why its important to meditate on death; how to start with Deity Yoga; how wrathful Deities can be misunderstood; and the role of the internet in Dharma teachings.”