By and large, we interact with who and what is around us through our senses.
So what we see, hear, touch, smell and taste will influence and form our interactions with others and with the other things around us.
Hence by our perceptions, we make our conclusions and decisions.
But that also means that what we perceive must be processed correctly otherwise our conclusions and decisions will be wrong.
In the gospel, the disciples thought that Jesus was talking about bread when Jesus warned them to keep their eyes open and to be on their guard against the yeast of the Pharisees and the yeast of Herod.
Jesus had to ask them, "Have you no perception?" Obviously the disciples do not understand what they see and what they hear.
In the 1st reading, the people could not perceive that they were sinning greatly against the Lord.
Their hearts were hardened and coarsened by wickedness and sin and they cannot understand the evil they were doing.
Let us pray that the Lord our God will soften our hearts with His love so that we will always be able to perceive His presence and do what is pleasing in His eyes.