You can’t know what you don’t know, because much of what you don’t know is not what you can’t know.

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We can become able to know, but only after we know what it means to be unable to know.

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It is not the unknowable-in-principle that bothers us: it is that ring of as-yet-unknowable between the solid ground of the knowable (with all its knowledge) and the unknowable that makes us anxious. Of course, it is only that ring that shows us what unknowable-in-principle really means. To most people unknowable-in-principle, is not a principle but permission to ignore.