How a Buddhist gets any new information regarding the teaching? There are three basic groups of inputs: own experience stemming from own practice, information from textual sources (scriptures of Buddhism, other texts on Buddhism, Dhamma), information from authoritative people (Buddhist teachers, Sangha). Regardless how we first learnt of Dhamma the three sources sooner or later appear in everyday life of the person.
Finding a right balance between them is extremely important. I have seen so many extremities like accepting only the word of the Teacher and not practicing at all or accepting only the word of the Teacher, practicing but never reading any suttas. Or only practicing and drawing all conclusions from the practice only. Or any other combinations of one or two sources from the three.
Using only one or two sources creates various delusions, hamper or completely stops the progress on the Path to Enlightenment. A teacher may make mistakes. A textual source may be interpreted incorrectly. Own practice may be delusive by itself. Sometimes all three are used but not equally.
I believe it is important to make use all of them and use equally. Whatever your practice produce should be questioned and verified against texts (suttas) and words of Teachers. Whatever you hear from a Teacher should be questioned and verified against suttas and own practice. Whatever you read in a sutta should be questioned and verified against two other. Then we reach a truly balanced approach and build a strong foundation for moving down the Path.
It is been noticed many times that Pali Canon extensively use ideas and conceptions borrowed from Vedas and Upanishads. At that time the ideas and analogies were obvious to any educated student of Buddha’s lectures without any explanations. They were leveraged by Gautama to convey his ideas apprehensively. The analogies was lost with time and the meaning of them is not clear for a reader nowadays. Some of the analogies might even stay completely unnoticed.
Pali canon texts often compare an Arahant with a palm stump (MN 72, overall more than 70 times). Sometimes it is followed by the statement that the stump is not able to give growth anymore. ucchinnamūlaṁ – cut off at the root (some translations incorrectly translate it as “destroyed roots”) Some suttas applies the same idea to a forest (SN 7.17). A modern meticulous reader having a bit of gardening skills might get confused here as a tree stump normally gives new branches very soon if the roots are not removed. The answer here is that palm trees unable to grow new branches being cut off at the root. But it is not the end of the story.
At Buddha’s times the notion of a tree with its roots was a very familiar and recognizable analogy for one more reason. The ninth brahmana of third chapter of Brihadaranyaka Upanishad (dated around or little earlier than suttas of Pali Canon) compares a person to a tree with the root of a man being his Self. The trunk and branches of the tree are false personal identity, created by the Self, rooted in the true Self and all that we consider as a being (a visible part like we consider visible part of a tree to be the tree). The death of the being is compared to the withering of the trunk and branches, and rebirth is when a tree grows again from a trunk, from roots.
Therefor a tree cut-off at the root meant that any visible false Self should be abandoned, cut off, extinguished and by means of it to end rebirths in any of the samsaric worlds. Removing the root was not an option according to Buddha though…
Sometimes people ask why is it so important to figure out what were true Buddha’s words, what was the Early Dhamma if there have been living so many enlightened Teachers since Buddha’s age? The Teachers explain us the Dhamma and teach us according to their traditions, schools and lineages and thus convey the true meaning of the Buddha words they say. Thus they equal words of teachers and Buddha’s own words. This is how the commentary tradition started. What Buddha himself thought about this?
Staying near Sāvatthī. “Monks, there once was a time when the Dasārahas had a large drum called ‘Summoner.’ Whenever Summoner was split, the Dasārahas inserted another peg in it, until the time came when Summoner’s original wooden body had disappeared and only a conglomeration of pegs remained. [The Commentary notes that the drum originally could be heard for twelve leagues, but in its final condition couldn’t be heard even from behind a curtain.]
“In the same way, in the course of the future there will be monks who won’t listen when discourses that are words of the Tathāgata—deep, deep in their meaning, transcendent, connected with emptiness—are being recited. They won’t lend ear, won’t set their hearts on knowing them, won’t regard these teachings as worth grasping or mastering. But they will listen when discourses that are literary works—the works of poets, elegant in sound, elegant in rhetoric, the work of outsiders, words of disciples—are recited. They will lend ear and set their hearts on knowing them. They will regard these teachings as worth grasping & mastering.
“In this way the disappearance of the discourses that are words of the Tathāgata—deep, deep in their meaning, transcendent, connected with emptiness—will come about.
“Thus you should train yourselves: ‘We will listen when discourses that are words of the Tathāgata—deep, deep in their meaning, transcendent, connected with emptiness—are being recited. We will lend ear, will set our hearts on knowing them, will regard these teachings as worth grasping & mastering.’ That’s how you should train yourselves.”
So while the commentaries and traditions might help us to understand Buddha’s words better, we should first figure out what were the original Buddha words and compare any teachings we have heard (whatever famous and popular the teacher is) to the most extant layers of early suttas. If they match then the teacher’s doctrines should be accepted if not the Buddha words should be most important to us.
That is why it is extremely important for us to figure out what was the original Buddha’s words, the Early Dhamma.