Outward motion of the nebula associated with the symbiotic variable R Aquarii was suspected by Hubble1 and confirmed by Baade2, who estimated its ejection ~600 yr ago. A new feature of the nebulosity near the star appeared between 1970 and 1977 as found by Herbig from direct plates obtained with the 3-metre telescope at Lick Observatory. The `spike' or `jet' so-called by Wallerstein and Greenstein3 appears as a protrusion from the central star. The observational properties of the jet in both the optical and radio are described by Sopka et al.4. The near UV image obtained in 1980 by Herbig and the VLA radio map4 are shown combined in Fig. 1. Here we suggest that the jet is the result of supercritical accretion of mass transferred from the cool 387-day period Mira to the hot companion in a highly elliptical orbit. Ancient Japanese astronomical records suggest a nova outburst in AD 930 may be associated with R Aquarii which formed the outer extended nebulosity. The jet may help explain the outbursts of this object as well as the excitation of the R Aquarii nebula.