John Muir says that the wood in the Big Trees has an endurance almost equal to that of granite, and gives the following illustration. He cut a piece of sound wood from the trunk of a fallen monarch that had been lying upon the earth several hundred years. In falling, the trunk of this Big Tree was cracked across in a number of places. Into these cracks fire ate its way each time a forest fire swept the locality. Each of these fires probably was separated from the following one by a number of years, and it probably took a great many burns to cut this slow-burning wood into sections. But at last this was done. Between the ends of two of these sections a fir tree took root and grew. After all these years, and after the fir tree had lived three hundred and eighty years, the sections of the Big Tree still lay upon the ground, apparently as sound as the day the tree fell. All Big-Tree groves appear to have gone through forest fires. It is probable that most of these groves have been repeatedly fire-swept. Many of the trees show fire-scars that cannot be entirely healed for centuries. The Big Tree has been called the noblest of a noble race. Its enormous size, its excellent proportions, its serenity, its steadfastness, its age, make it the most impressive living object. John Muir, in commenting on the imperishable nature of the sequoia, says he feels confident that if every one of these trees were to die to-day, numerous monuments of their existence would remain available for the student for more than ten thousand years. But the Big Tree is not verging toward extinction. Its greatest danger is from general destruction by man. The Big-Tree area has not diminished, but probably has slightly increased in the last few thousand years. Seeds sprout readily and young trees grow vigorously. John Muir thus comments concerning the tree and its distribution:-- The Big Tree (_Sequoia gigantea_) is Nature's forest masterpiece, and, so far as I know, the greatest of living things. It belongs to an ancient stock, as its remains in old rocks show, and has a strange air of other days about it, a thoroughbred look inherited from the long ago--the auld lang syne of trees. Once the genus was common, and with many species flourished in the now desolate arctic regions, in the interior of North America, and in Europe, but in long eventful wanderings from climate to climate only two species have survived the hardships they had to encounter. The Big Trees probably were discovered by General John Bidwell in 1841. John Muir studied them for years, and then gave to the world an accurate account of them.