We are Arms of the Lord, because we are fighting against the influence of Maya, or the non-devotees. Actually we the Krishna Conscious people are soldiers of the Lord, or Arms of the Lord, and because we are energy at the same time, because all living entities are energy of the Lord, so energy is always kept on the left side. As you have seen, Radharani is also on the left side of the Lord, and similarly, Laksmiji is also kept on the left side of the Lord, so we are also marginal energy, not exactly like Radharani or Laksmiji, but we are superior energy than matter, or material energy, so we should keep ourself always on the left side of the Lord, and let us act as His Arms, or army.

From Srila Prabhupada’s letter to Brahmananda — Montreal 22 August, 1968