He leads them, as his custom is, from low things to high. Fields and harvest here express the great number of souls, which are ready to receive the word. The eyes are both spiritual, and bodily ones, for they saw a great multitude of Samaritans now approaching. This expectant crowd he calls very suitably white fields. For as the corn, when it grows white, is ready for the harvest; so were these ready for salvation. But why does He not say this in direct language? Because by making use in this way of the objects around them, he gave greater vividness and power to His words, and brought the truth home to them; and also that His discourse might be more pleasant, and might sink deeper into their memories.
Reproduced in full. Translation: Oxford 1841 (Newman), public domain (Public domain).
Also cites: Hom. xxxiv. 2