“With regard to the Mystic Law, benefit means wiping out evil and bringing about good (cf. OTT, 148). The daimoku of the Lotus Sutra—Nam-myoho-renge-kyo— eradicates the fundamental evil inherent in life and gives rise to fundamental good.
That’s why, by chanting daimoku, we can eliminate all forms of evil karma in an instant and manifest immeasurable good fortune and benefit.
By chanting Nam-myoho-renge-kyo a single time, we ordinary, unenlightened beings—plagued by problems, doubts, and suffering—can positively transform our circumstances in accord with the principle of “changing poison into medicine” and attain a state of life filled with hope, courage, and peace of mind. To ordinary people, this is truly an astonishing and unfathomable teaching. And because it is the wondrous and mysterious law to which the Buddha became enlightened, it is called the Mystic Law.”
 The Daishonin writes: “The element ku in the word kudoku [benefits] . . . refers to the merit achieved by wiping out evil, while the element toku or doku refers to the virtue one acquires by bringing about good” (OTT, 148).
Daisaku Ikeda: Letcture on an extract from the Gosho ‘The Daimoku of the Lotus Sutra’
 The principle that earthly desires and suffering can be transformed into benefit and enlightenment by virtue of the power of the Law. This phrase is found in a passage from Nagarjuna’s Treatise on the Great Perfection of Wisdom, which mentions “a great physician who
can change poison into medicine.” This phrase is often cited to show that any problem or suffering can be transformed eventually into the greatest happiness and fulfillment in life.