Guru, sadhu, shastra tattva

In Krishna Consciousness or bkakti yoga or vedic understanding of the metaphysics, the three checkpoints used to ascertain truth is guru, sadhu and shastra. Although all three have to coincide still we need a reference point to begin with and that is the scriptures or shastra. In other words, the sadhu and guru must agree with the shastra or scriptures. Why? Because shastra is considered 'apaurusheya' or in other words not tainted by mundane dualities of time and space. It does not change as we change. Also, just as Narayana existed before creation, shastra existed before creation as well. Before creation there was no time so the vedic scriptures existed before time (outside imperfections). So once we come within time, even pure devotees need to align with shastra. That is the method or the way to ascertain tattva or truth.

Another aspect of shastra is that although we may study scriptures over time in piece-meal still the conclusions must be accepted in whole. It is like stitching a quilt with different colored patches. The quilt is one big blanket but stitched over time with different patterns. Similarly, there may be differences in different scriptures presented to different people and if we just look at the details in difference ignoring the whole, then we see a quilt for its patches or patterns and not as a whole fabric as a blanket. Therefore the conclusions from the scriptures must be holistically derived. Any contradictions we may encounter has to be understood as a detail.

For example, in some scriptures, Siva or Durga are glorified as Supreme. This is a detail that needs to be addressed and visited. But the overall conclusion is that Vishnu is Para or beyond materialism but Siva and Durga are Supreme within the creation (but not outside of it). Therefore the overall conclusion is Vishnu is the Supreme.  This is the quilt as a blanket vision. Another example is always remember Vishnu and never forget Him and do whatever is favorable in regards to that. This is the blanket vision. So other details such as guru tattva, sadhana bhakti, qualities of a disciple such as humility, tolerance etc should serve the blanket truth to always be connected to Vishnu. But if separate them, then we will give importance to guru's instructions more than God's instructions and elevate guru to God in a subtle manner. We will practice sadhana bhakti sentimentally (can lead to dogmatism) and humility as self-righteousness. So like this when we separate the singular individual truths from the blanket truths, we will eventually deviate and fall.

Therefore, we have to understand shastra as center and guru and sadhu are subservient to shastric conclusions and that we have to accept vedanta (conclusions) holistically and not piece-meal.

The actual center is the śāstra, the revealed scripture. If a spiritual master does not speak according to the revealed scripture, he is not to be accepted. Similarly, if a saintly person does not speak according to the śāstra, he is not a saintly person. The śāstra is the center for all.
- Purport by Srila Prabhupada CC Madhya 20.352