The Greek word pachýnō, represented by G3975, means to thicken or fatten. Figuratively, it is used to describe a heart that is stupefied or rendered callous, translated as "wax gross." This term appears only 2 times in 2 verses, yet it is central to understanding the concept of spiritual hardness and resistance to God's word.
In its biblical usage, G3975 describes a specific spiritual condition. In both Matthew 13:15 and Acts 28:27, the phrase "this people's heart is waxed gross" introduces a sequence of spiritual decline. This callousness of the heart is presented as the reason the people are unable to perceive truth. It leads to their ears being dull of hearing and their eyes being closed, which in turn prevents them from seeing, hearing, understanding, being converted, and ultimately, being healed by God.
Several related words from the context of its occurrences clarify the consequences of a heart that has "waxed gross":
- G917 baréōs (dull): This adverb, meaning "heavily," is used to describe the ears of those whose hearts are hardened. They become dull of hearing, unable to receive the divine message clearly Matthew 13:15.
- G4920 syníēmi (understand): To understand or comprehend is a function of a receptive heart. This is the opposite of the state described by G3975, as a gross heart prevents one from understanding, a key step toward conversion Acts 28:27.
- G1994 epistréphō (convert): This verb means to turn or revert. The purpose of spiritual perception is to convert or turn back to God, but this is impossible when the heart is hardened and unable to understand Matthew 13:15.
- G2390 iáomai (heal): To cure or make whole, this is God's final intended action, which is blocked by the people's condition. If they would convert, God would heal them Acts 28:27.
The theological weight of G3975 centers on the nature of spiritual resistance.
- The Root of Insensibility: The term identifies a thickened, callous heart as the origin of spiritual insensitivity. It is not merely a lack of knowledge but a state that makes the faculties of seeing (G1492) and hearing (G191) ineffective for spiritual matters Matthew 13:15.
- A Willful Condition: The state of having "waxed gross" is linked to a deliberate action of closing the eyes (G2576). This implies that the spiritual dullness is a chosen state, a self-imposed barrier against the truth to avoid the need to be converted.
- The Obstacle to Salvation: A heart that has waxed gross prevents the entire process of salvation. It stops a person from seeing, hearing, and understanding, which are the necessary precursors to being converted (G1994) and healed (G2390) by God Acts 28:27.
In summary, G3975 is a potent term that describes more than simple ignorance. It signifies a deep-seated, willful hardening of the heart that renders a person incapable of perceiving spiritual truth. As shown in Matthew 13:15 and Acts 28:27, this condition creates a definitive barrier to the understanding, conversion, and healing that God offers. It is a critical word for understanding the profound consequences of spiritual apathy and resistance.