"Make the heart of this people fat"

The Old Testament Institute Student Manual says something that caught my attention today.  I was reading about Isaiah 6:9-13.  It says "The words the prophet Isaiah was commissioned to deliver were in part to bring the people to a full accountability for their choices, so that they would be left without excuse. . . The command to 'make the heart of this people fat, . . their ears heavy, and shut their eyes' is used to describe the process of making the people accountable. . . . 'There is a self-hardening in evil . . . . sin from its very nature bears it own punishment. . . . An evil act in itself is the result of self-determination proceeding from a man's own will.' (quoted from Keil and Delitzsch; Commentary, 7:1:201). An individual cannot resist or reject the truth without eventually becoming spiritually hardened (see History of the Church 4:264)."  So time again for self examination - is there some truth, some facet of gospel living, some Christlike characteristic, that I am resisting or rejecting?