St John Chrysostom says: "[Sacrifice] was once for all offered, [and] carried into the Holy of Holies. This is a figure of that [sacrifice] and this a remembrance of that. For we always offer the same, not one sheep now and tomorrow another, but always the same thing; so that the sacrifice is one.... Christ is one, everywhere, being complete here and complete there also, one Body. As then while offered in many places, He is one body and not many bodies; so also He is one sacrifice. He is our High Priest, Who offered the sacrifice that cleanses us. That which we offer now also, which was then offered, which cannot be exhausted. This is done in remembrance of what was then done. For (He says) 'do this in remembrance of me' (Luke 22:19). It is not another sacrifice, as the High Priest, but we offer always the same, or rather we perform a remembrance of a Sacrifice." 

St John Chrysostom, THE NICENE AND POST-NICENE FATHERS First Series, Vol. XIV, 
Homily 17 on Hebrews 9:24-26, page 449.