In a letter to Montgomery Meigs, Thomas Crawford explained the symbolism of the left side of the pediment:

The opposite half of the pediment is devote[d] to the effects of civilization and liberty. The first figure represents the soldier. I have given him this important position, as [our] freedom was obtained by the sword and must be preserved by it. I have clothed this statue with the military costume of our revolution as being suggestive of our country's struggle f[or] independence...His hand in the act of drawing the sword indicates the readiness [and] determination of our army to protect America from insul[t].

Adjoining the soldier I have placed the merch[ant] sitting upon the emblems of commerce. His right ha[nd] rests upon the globe to indicate the extent of our trade. The anchor connects his figure with tho[se] of two boys, who are advancing cheerfully forward to devote themselves to the service of their country. The anchor at their feet is an easily understood emblem of hope for them in the future. behind them si[ts] the teacher, emblematic of scholarship. he is instruction a child, whose career is shown by the dance of the boys his school mates. The mechanic completes this group. He rests upon the cogwheel, without which machinery is useless. In his hands are the implements of his profession, the hammer and compass; at his feet are seen [?] sheaves of wheat, expressive of fertility, activity, and abundance, in contradistinction to the emblem of the Indian extinction-the grave-at the corresponding angle of the tympanum.

View Crawford's sketch of the Pediment's left side.