Interesting connection between rhetoric and spirituality. It reminded me of this scene from Exodus:
Moses said to the Lord, “Pardon your servant, Lord. I have never been eloquent, neither in the past nor since you have spoken to your servant. I am slow of speech and tongue.”
The Lord said to him, “Who gave human beings their mouths? Who makes them deaf or mute? Who gives them sight or makes them blind? Is it not I, the Lord? Now go; I will help you speak and will teach you what to say.”
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The connection between spirituality (the divine) and strong rhetoric that Rickert alludes to here is made literal in this scene; the power of God is in His language and the eloquence he grants to Moses. The strong words granted to Moses/Aaron by God allow the prophet to guide the souls of the Egyptians toward Hebrew liberation.