I've often thought how obsessions start. Comparing this with where they end up can show quite a dramatic difference. The differance could be so great that it would be impossible to see the journey of the 'downward spiral'. (I'm using the word 'down', but I feel obsessions can also be uplifting. Direction really doesn't matter in this context.)
It's that trigger event, that nexus in the space-time continuum, that is the key. I can't help but look forward to the downward spiral.