Nichiren writes in The Three Treasures written to his beloved disciple the samurai Shijo Kingo:
"It is rare to be born a human being. The number of those endowed with human life is as small as the amount of earth one can place on a fingernail. Life as a human being is hard to sustain—as hard as it is for the dew to remain on the grass. But it is better to live a single day with honor than to live to 120 and die in disgrace. Live so that all the people of Kamakura will say in your praise that Nakatsukasa Saburō Saemon-no-jō is diligent in the service of his lord, in the service of Buddhism, and in his concern for other people. More valuable than treasures in a storehouse are the treasures of the body, and the treasures of the heart are the most valuable of all. From the time you read this letter on, strive to accumulate the treasures of the heart!"
The heart of the Buddha’s lifetime of teachings is the Lotus Sutra, and the heart of the practice of the Lotus Sutra is found in the “Never Disparaging” chapter. What does Bodhisattva Never Disparaging’s profound respect for people signify? The purpose of the appearance in this world of Shakyamuni Buddha, the lord of teachings, lies in his behavior as a human being."
And in Nichiren's Gift of Rice Gosho he writes:
"In worshiping all the deities and Buddhas, the word namu is put ahead of their names. To explain exactly what namu means, namu is a word from India. In China and Japan it is translated as “dedicating one’slife.” “Dedicating one’s life” means to offer one’s life to the Buddha. In accordance with their status, some have wives and children, relatives, fiefs, and gold and silver, while others have no treasure. Whether one has wealth or not, no treasure exceeds the one called life. This is why those known as the sages and worthies of ancient times offered theirlives to the Buddha and then became Buddhas.
The boy Snow Mountains offered his body to a demon to receive a teaching composed of eight characters. Bodhisattva Medicine Kingburned his arms as an offering to the Lotus Sutra. In our own country too, Prince Shōtoku peeled off the skin of his hand and copied the Lotus Sutra on it, and the sovereign known as Emperor Tenji burned his third finger as an offering to Shakyamuni Buddha. Because these things are the affairs of worthies and sages, they are impossible for us to do.
However, as for the matter of becoming a Buddha, ordinary people keep in mind the words “earnest resolve” and thereby become Buddhas. When we carefully consider what exactly earnest resolve refers to, it is the doctrine of observing the mind. When we inquire into what exactly the doctrine of observing the mind refers to, it means that offering one’s only robe to the Lotus Sutra is equivalent to peeling off one’s skin; and that in a time of famine, offering the food that is the only means for sustaining one’s life that day to the Buddha is offering one’s life to the Buddha. The blessings from this are in no way inferior to those Bodhisattva Medicine King gained by burning his arms, or the boy Snow Mountains gained by offering his body to a demon. Thus, what is appropriate for sages is offering in actuality [offering one’s life itself for the Law]. What is appropriate for ordinary people is offering in principle [sincerely offering what is important to one’s own life]. This is the teaching called the pāramitā of almsgiving for the observation of the mind that is set forth in the seventh volume of Great Concentration and Insight.
The true path lies in the affairs of this world. The Golden Light Sutra states, “To have a profound knowledge of this world is itself Buddhism.” The Nirvana Sutra states, “All of the non-Buddhist scriptures and writings in society are themselves Buddhist teachings, not non-Buddhist teachings.”
When the Great Teacher Miao-lo compared these passages with the one from the sixth volume of the Lotus Sutra that reads, “No worldly affairs of life or work are ever contrary to the true reality,” he revealed their meaning and pointed out that although the first two sutras are profound, since their meaning is still shallow and fails to approach that of the Lotus Sutra, they relate secular matters in terms of Buddhism, whereas the Lotus Sutra explains that in the end secular matters are the entirety of Buddhism.
The essence of the sutras preached before the Lotus Sutra is that all phenomena arise from the mind. To illustrate, they say that the mind is like the great earth, while the grasses and trees are like all phenomena. But it is not so with the Lotus Sutra. It teaches that the mind itself is the great earth, and that the great earth itself is the grasses and trees. The meaning of the earlier sutras is that clarity of mind is like the moon, and that purity of mind is like a flower. But it is not so with the Lotus Sutra. It is the teaching that the moon itself is mind, and the flower itself is mind. You should realize from this that polished rice is not polished rice; it is life itself."
Here we have a seeming contradiction. The treasures of the storehouse or material treasures are at once labeled inferior by Nichiren and subsequently described as life itself. The "treasures of the storehouse" may be considered the cars we drive, the various houses in which we live, and the money and jewels we possess. Exceptions to the inferiority of material treasures are the food, clothing, and shelter which sustain life and which may be considered life themselves and equal to treasures of the heart.