"I saw that God would work for the salvation of His people: that this misguided man would soon manifest himself, so that all the honest in heart would see that he was not actuated by a right spirit, and that his career would soon close. Soon afterward the snare was broken, and he had but little more influence over the brethren. He denounced the visions as being of the devil, and continued to follow his impressions, until his mind was deranged and his friends were obliged to confine him. At last he made a rope of some of his bed clothing, with which he hanged himself, and his followers were brought to realize the fallacy of his teachings. LS 86.4"
"Wherefore by their fruits ye shall know them."
The EGW passage describes a man whose actions and ultimate demise revealed the falsity of his teachings. This aligns with the principle in Matthew 7:20 that one can discern truth from falsehood by observing the 'fruits' or consequences of a person's actions and teachings.