I strongly think that for every depression there is a reason. Or multiple. Doesn't matter really. If you find it and deal with it, it's over. Medication is only treating the symptoms, but not the cause.
I agree about medicationonly treating the symptoms and about having to find teh reason.
Unfortunately, even if you find the root of the problem, you'll still always be prone to relapses. Depression is like lip herpes in this respect. You can treat it and propably be without symptoms for years but you can't heal it forever.