“All brutes are irrational;
Some beings that can speak are brutes,”
which is clearly not the natural course of thought; indeed the conclusion which would then follow, “Some beings that can speak are irrational,” would have to be converted in order to preserve the conclusion which the [pg 301] third figure gives of itself, and at which the whole course of thought has aimed. Let us take another example:
All alkalis float in water;
All alkalis are metals:
Therefore some metals float in water.
Figure 1
Figure 2