They said therefore to him, "What must we do, that we may work the works of God?"
      [2.] What is meant by  eating this flesh  and  drinking  this  blood,  which is so necessary and beneficial; it is certain that is means neither more nor less than believing in Christ. As we partake of meat and drink by eating and drinking, so we partake of Christ and his benefits by faith: and  believing in Christ  includes these four things, whicheating and drinking  do:—First,  It implies an  appetite  to Christ. This spiritual eating and drinking begins withhungering  and  thirsting  (Matthew 5:6), earnest and importunate desires after Christ, not willing to take up with any thing short of an interest in him: "Give me Christ or else I die."  Secondly,  An  application  of Christ to ourselves. Meatlooked upon  will not nourish us, but meat  fed upon,  and so made  our own,  and as it were  one with us.  We must so accept of Christ as to appropriate him to ourselves:  my Lord, and my God,  ; John 20:28.  Thirdly,  A  delight  in Christ and his salvation. The doctrine of Christ crucified must be  meat and drink  to us, most pleasant and delightful. We must feast upon the dainties of the  New Testament in the blood of Christ,  taking as great a complacency in the methods which Infinite Wisdom has taken to redeem and save us as ever we did in the most needful supplies or grateful delights of nature.  Fourthly,  A  derivation of nourishment  from him and a dependence upon him for the support and comfort of our spiritual life, and the strength, growth, and vigour of the new man. To  feed upon Christ  is to do all  in his name,  in union with him, and by virtue drawn from him; it is to live upon him as we do upon our meat. How our bodies are nourished by our food we cannot describe, but that they are so we know and find; so it is with this spiritual nourishment. Our Saviour was so well pleased with this metaphor (as very significant and expressive) that, when afterwards he would institute some outward sensible signs, by which to represent our  communicating  of the benefits of his death, he chose those of  eating  and  drinking,  and made them  sacramental  actions.