With ignorant mind you cannot approach the omniscient mind. Like without the fuel in the car you cannot reach your destination. Even if you have the car, if you don’t have the fuel then you cannot reach to the desirable place.
-Lama Zopa Rinpoche
In this talk, Lama Zopa Rinpoche explains why we work with so many different aspects of the Buddha during our practice. By taking refuge in these varied aspects of the Buddha’s enlightenment, we open ourselves to their particular attributes, guidance and inspiration. For example, cultivating a relationship with Manjushri creates the conditions to increase our wisdom-knowledge and with White Tara we can increase the span of our perfect human rebirth. Cultivating the appropriate conditions help us overcome our personal karmic obstacles on the path to enlightenment for the benefit of others. Rinpoche gave these teachings at the Fourteenth Kopan Meditation Course in 1981. You can read along with the transcript at https://www.lamayeshe.com/article/chapter/lecture-2-manjushri-why-there-are-different-aspects-buddha