How should we react to the weakness of our human nature, especially our weak imagination? St Teresa says: react with gentleness. Our imagination (= "thought") bears the effects of original sin. Instead of being perfectly docile to reason (= "understanding"), our imagination often goes off "on its own" in many directions, confused and excited. This (almost) independent imagination is part of the lack of original justice or harmony within the human person. The loss itself of original justice -- through the sin our own first parents -- is not the personal fault of you or me. The fact that we have bodily and mental sufferings (at all) in not our own personal fault. The fact that there is a devil who tempts us is not our own personal fault.

Yes, we have personal sins. Yes, we have committed sins that aggravate our situation; but the fact of original sin and the angelic sin of the devil and the fallenness of our world, these are not our fault, our personal responsibility. We are like sheep without a shepherd. This is why Jesus came! 

He has compassion on us. May we be gentle with ourselves and our wild imaginations (= thought) as we pray for the manifestation of His love (to our understanding and will).