In reflecting upon the plight of the fallen servant, the image Julian is surveying as a metaphor for sin, Julian observes the state of the servant's mental state having sustained his injuries:
...his reason was blinded and his mind stunned to such an extent that he had almost forgotten his own love for the lord.
This is the fourth great pain of sin, a mind blinded and stunned by our injuries, causing us to lose sight of God.
What Julian is describing here are what theologians call the noetic effects of sin. The way sin twists our thoughts and distorts our perceptions. The way sin makes it difficult to see clearly. Myself, others, and the world. We can stumble because of weakness, yes, but we can also stumble because we're walking in darkness.
But what especially strikes me about Julian's description is the word "stunned." Sin stuns the mind. The shock of our pain and hurt blocks our ability to think clearly. Getting injured radically affects our mental processing. Our hurt twists our perceptions. Our pain causes us to panic.
I find in all this a very evocative way to ponder our lives. I don't think people wake up in the morning with malevolent intentions or well-laid plans that are transparently self-defeating. I think, for most of us, we're just banging into things with no real rhyme or reason. We're stumbling around. We do a lot of stuff that makes no sense or is patently stupid. And it's interesting to look at all that behavior as less a product of willful decision-making than the actions of a person who is dazed and confused, stunned and concussed.