Adam Clarke on Matthew 16:11

How is it that ye do not understand - We are not deficient in spiritual knowledge, because we have not had sufficient opportunities of acquainting ourselves with God; but because we did not improve the advantages we had. How deep and ruinous must our ignorance be, if God did not give line upon line, precept upon precept, here a little and there a little! They now perceived that he warned them against the superstition of the Pharisees, which produced hypocrisy, pride, envy, etc., and the false doctrine of the Sadducees, which denied the existence of a spiritual world, the immortality of the soul, the resurrection of the body, and the providence of God.