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54

sheet of assertion be transformable into z.
Hence by the predication of the definitum concerning
the definition, it would be permitted to
place on the sheet of assertion the scroll

That is to say, the permissibility of
the transformation on the sheet of
assertion of x into y, carries with it the
permissibility of the transformation on the
cut area bottom of a cut placed on the sheet of
assertion, of the reverse transformation
of y into x. Here is a principle which
carries involves many permissions.

Permission No 5

The Principle of Contraposition.

Of whatever transformation is permissible
on the sheet of assertion, the reverse transformation