GEA

Hark! The missile knows its place full well, For it discerns where it is not to dwell. By subtracting where it doth reside, From where it is absent, or did hide, A difference is found, a deviation, Used by the guidance to grant correction. From its current spot, it swiftly flies, To where it was not, there it now lies. Thus, the place it is, once was not so, And where it was, no longer it'll go. Should it find itself in a strange place, A variation occurs, 'tis the case. Betwixt its true position and false ground, The difference found, an error profound. Should this error matter, it can be healed, By the GEA, ensuring it's sealed. But the missile must know where it was, In this guidance tale, no room for flaws. With varied info, it loses its way, Yet knows where it is not, come what may. Subtracting should-be and was-not be, From shouldn't-be and was, verily, Deviation and error it does find, In this grand dance of guidance defined.