Lesego works as a messenger and driver for the University of Summer. Her job is to make deliveries on behalf of the University of Summer, mainly for the office of the principal, Prof Bontle. While driving at 100km/h along a freeway to make a delivery at the University of Winter, Lesego suffered a heart attack that caused her to lose consciousness immediately. Her vehicle swerved out of control and crashed into a car next to hers, moving in the same direction. Mpho, the driver of the other car, sustained bodily injuries and was hospitalised for a period of six months. After his discharge from hospital, Mpho instituted a delictual action against the University of Summer, the employer of Lesego. Prof Bontle on behalf of the University of Summer raised the defence that Mpho's injuries were not caused by any conduct of its employee, Lesego, because at the time of the collision, Lesego was unconscious. Discuss the merits of this defence with specific reference to the theoretical background thereof.