DC> I had understood aasava to be an *outflow* rather than an inflow.
It's a common error based on PED. Somehow nobody cares to notice the
asterick before aasrava in the PED article.
Pali aasava has two meanings corresponding to two Sanskrit words:
- aasraava, discharge from a sore, effluent from flower or tree.
This meaning is quite literal and is not used fuguratively.
- aasrava, inlet, leak in the doors of perception, through which
craving flows in. Mr. Rhys-Davids apparently has not found this
meaning in Sanskrit dictionary (marking it with asterick), yet it is
clearly explained in Monier-Williams dictionary and Jain texts.
DC> The sense I get is of aasava being a fundamental, underlying tendency
DC> in the mind that drives all other defiled mental activity.
Yes, aasavaa serve as a condition for defilements. They are the ways in
which craving affects other mental processes. For example, have you
noticed, that when you crave for somebody or hate somebody, you view
him very differently. That's an influence of craving (ta.nhaa) on
apperception (sa~n~naa).
DC> I think it may also have been translated as "cankers" as well
DC> as "taints" in some early translations?
Yes, for example in translations by Ven. Soma Thera.