Musar על כתובות 224:3

When the Midrash described the six attributes that were withheld from earth after the sin, three of these were attributes possessed by Adam such as the כתנות אור, the garments woven of "light,' referred to in the Midrash as זיוו, his 'life,' i.e. his unlimited lifespan, and his קומתו, exceptional physical height and stature. All these will be restored in the period under discussion. At that time all trees will not only bear fruit but produce wood that tastes just as the fruit, and the original “light” will be restored to this world.

Let us return to the statement that by their actions the righteous can transform the attribute of Justice into the attribute of Mercy and that the reverse is true of the actions of the wicked. This is the deeper meaning of 26,5: וישבתם לבטח בארצכם, "you will dwell safely in your land." Such a state is achieved through the refinement of matter, i.e. converting ארץ earth because of the בטח, the way one relates, i.e. relies on G–d. When your life on earth is one in which your enjoyment is motivated by the desire to serve G–d better, then the land itself assumes a spiritual dimension. This is why the prophet Isaiah 11,9 may have chosen to describe such a future period as כי מלאה הארץ דעה את ה', that the earth will be full of knowledge of the Lord." This is the reason why we have numerous allusions to this thought in פרשת בהר, where the sanctity of the land is discussed. The subject is always the sanctity of matter, not just the sanctity of the spirit. In פרשת בחוקותי the emphasis is merely shifted to the future when we have statements such as ועץ השדה יתן פריו, "and the tree of the field will yield its fruit" (26,4). This promise does not speak about the fruit-bearing trees yielding their harvest; rather it promises that as a result of sanctifying the land through our conduct the "tree of the field," (not the orchard) will also produce fruit fit to be consumed by man. The mystical dimension of all this is that matter will be perceived as possessing an intelligence of its own.