JUSTICE STEIGMANN delivered the opinion of the court:

In November 1998, a jury convicted defendant, Robert Francis, of aggravated assault (720 ILCS 5/12-2(a)(1) (West 1998)). The trial court later sentenced him to probation subject to certain conditions. Defendant appeals, arguing that the trial court erred by refusing his request to instruct the jury on self-defense. Because we agree, we reverse and remand for a new trial.

I. BACKGROUND

The aggravated assault charge against defendant alleged that on September 1, 1998, he, in committing an assault, used a deadly weapon, "in that he knowingly pointed a knife at Donald Maybell[] and swung the knife at Donald Maybell, thereby placing Donald Maybell in reasonable apprehension of receiving a battery." At defendant's trial, Maybell testified as follows concerning the September 1 incident.

Maybell and defendant lived in the same neighborhood and occasionally socialized together. Sometime before September 1, Maybell loaned defendant $170. Defendant promised Maybell that he would pay him back on September 1, when defendant expected to receive his disability check.

On September 1, Maybell visited defendant's residence to ask about the money he was due. Defendant told Maybell that the state had "messed his check up" and he had not received it.

Maybell returned to his home, where Thomas Johnson was visiting with Maybell's girlfriend and her two children. Sometime later, Maybell noticed defendant's wife, Emma, from whom defendant was separated, pick defendant up from his residence and drive away. Maybell had noticed that Emma usually picked defendant up on the days that he received his check from the state. Because Maybell did not believe that defendant had not received his check, he decided to follow Emma's vehicle. Johnson joined him.

Emma drove to a grocery store that had a bank inside. When defendant got out of Emma's vehicle and went inside the store, Maybell asked Johnson to go inside to see if defendant cashed a check. Johnson entered the store and, when he returned, he told Maybell that defendant had cashed a check.

At that point, Maybell saw defendant leaving the store and blew his car horn. Defendant went over to Maybell's vehicle, swore at Maybell, and accused Maybell of following him. Maybell responded that he just wanted his money and believed defendant had received his check.

Defendant screamed at Maybell, "You don't know who you are fucking with." He then pulled a knife from his back pocket and unfolded it. Maybell stepped out of his vehicle, put his arms in the air, and screamed "at the top of [his] lungs, 'I'm not threatening this man and this man has a knife on me.'" Defendant pointed the knife at Maybell and made some swinging motions in the direction of Maybell's face and stomach. Although the knife never actually touched Maybell, he described it as "about a