It taught me:

a) It's not a friendly love and light drug, it can be actually very mean and dark to you.

b) to treat it with respect (or Benzos, depending on your world view)

c) to stay away from drunk bearded hippies (or drunk persons in general? Could be my interpretation, not an actual teaching)

d) that it should be quantified and tested in a lab, unless the use is embedded in your local culture. Western ppl should be fine with a quantified DMT + MAOI mixture in a cap and Benzos nearby, no need to emulate the Shamans in the Amazon. That's what a Don Juan like vision told me on Rue & DMT.

Edit: ooops, _one_ thing... okay, chose the right one for you