| Sodium = sodium metal, | (1) |
| Metal = metal conducting electricity, | (2) |
we infer
Sodium = sodium metal conducting electricity, (3)
which, in the elliptical language of common life, becomes
“Sodium conducts electricity.”
The above is a syllogism in the mood called Barbara[60] in the truly barbarous language of ancient logicians; and the first figure of the syllogism contained Barbara and three other moods which were esteemed distinct forms of argument. But it is worthy of notice that, without any real change in our form of inference, we readily include these three other moods under Barbara. The negative mood Celarent will be represented by the example
| Neptune is a planet, | (1) | |
| No planet has retrograde motion; | (2) | |
| Hence | Neptune has not retrograde motion. | (3) |
If we put A for Neptune, B for planet, and C for “having retrograde motion,” then by the corresponding negative term c, we denote “not having retrograde motion.” The premises now fall into the forms
| A = AB | (1) |
| B = Bc, | (2) |
and by substitution for B, exactly as before, we obtain