Acharya Vaani
upadesho brahmaNastu sarveShAmeva muktaye | A.V 3.3.28
It has been said that brahma is the guru for all, sarasvati is the vidyA devatA and nArAyaNa is the pratipAdya devatA. One can understand the last two but a guru is one who teaches the vidyA. Brahma is not known to teach everyone such as oneself. So, how can brahma be the guru for all? To this we say, there are three types of gurus
1. upadeshakAs - direct teachers
2. sampradAyapravartakAs - those who are responsible for continuing the tradition
3. anugrAhakAs - those who help in the study by their blessings, inspiration etc.
Here one should note that, not everyone is eligible for direct upadesha of brahma. Though brahma is not the direct upadeshaka for ordinary souls, he is also called as their guru for being responsible for initiating the tradition by doing the upadesha to his direct disciples. Hence in the case of normal souls such as oneself brahma is sampradAyapravartaka guru. All others superior souls who are not direct teachers to lower souls such as oneself but are themselves upadeshaks to their direct disciples also fall in the sampradAyapravartaka category. Those who are neither upadeshakAs nor sampradAyapravartakAs but help in the study by their blessings, inspiration etc are called anugrAhaka gurus.
So, in this or the future births, one is sure to get upadesha from brahma if he is eligible, or from a guru ordained by brahma if he is not eligible for direct upadesha of brahma. In this way brahma is the guru of everyone.