Chapter 4 discusses Thomas’s account of original guilt. Infants are guilty only in an analogical sense. A human being with the use of reason is guilty in the proper sense when she commits a sinful act of her own volition; an infant is guilty in an analogical sense when she fails to receive original justice by Adam’s volition. The infant is in a moral middle ground, between the state of mortal sin and sanctifying grace (Scriptum II, d. 35, q. 2, a. 2, ad 2). She has not turned away from God, yet she needs grace nonetheless. Thomas’s explanation of infant guilt developed. He initially compared the guilt of original sin to an inherited disease (Scriptum II, d. 30, q. 1, a. 2). He later abandons this analogy and compares the infant to a homicidal hand. I defend Thomas’s view that the infant’s will is positioned between mortal sin and sanctifying grace. But I criticize his view of analogical guilt, arguing that receiving the effect of another’s sinful act cannot increase one’s own guilt.