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There is a story in the Pali Canon where the Buddha compares the Dharma to leaves on a tree. If I can give a very approximate quote to what I remember
The dharma that I have taught is just a handful of leaves. The Dharma is actually all the leaves in all the trees
So the point been that there is a lot more to the Dharma then what the Buddha is teaching at that point. Can anyone give the exact reference for that story - I'm fairly certain it is from the Pali Canon.