An illustrational form tells you through the intelligence immediately what the form is about, whereas a non-illustrational form works first upon sensation and then slowly leaks back into the fact.
It was in His flesh that Christ walked among us and it is His flesh that He has given us to eat for our salvation; but no one eats of this flesh without having first adored it . . . and not only do we not sin in thus adoring it, but we would be sinning if we did not do so.
John F.Kennedy gave probably the greatest inauguration speech ever that first time, but I guarantee you when he first walked out there he was thinking, "Goodness gracious this is big and I better be up to the task."