Self-portraiture

I assume Bergman's quotation about self-portraiture ('self-portraiture is something one should never get involved in, since it is wrong to lie even though one endeavours to tell the truth') is ironic, at least to some extent. It is wrong to lie even if you're trying to tell the truth: wrong to attempt with all your heart to be truthful but, inadvertently, or because of the nature of the material with which you are working, to miss it? Surely not. Of course, that's not what Bergman means: he's saying where self-representation is concerned, and therefore presumably self-understanding, good intentions do not amount to veracity. That's fair enough. But neither do they necessarily amount to mendacity.