in Thoreau’s Journal:

—To epigaea via Clamshell Hill. There is no such thing as pure objective observation.  Your observation, to be interesting, i. e. to be significant, must be subjective. The sum of what the writer of whatever class has to report is simply some human experience, whether he be poet or philosopher or man of science. The man of most science is the man most alive, whose life is the greatest event. Senses that take cognizance of outward things merely are of no avail. It matters not where or how far you travel, —the farther commonly the worse, —but how much alive you are. If it is possible to conceive of an event outside to humanity, it is not of the slightest significance, though it were the explosion of a planet. Every important worker will report what life there is in him. It makes no odds into what seeming deserts the poet is born. Though all his neighbors pronounce it a Sahara, it will be a paradise to him; for the desert which we see is the result of the barrenness of our experience. No mere willful activity whatever, whether in writing verses or collecting statistics, will produce true poetry or science. If you are really a sick man, it is indeed to be regretted, for you cannot accomplish so much as if you were well. All that a man has to say or do that can possibly concern mankind, is in some shape or other to tell the story of his love, ––to sing; and if he is fortunate and keeps alive, he will be forever in love. This alone is to be alive to the extremities. It is a pity that this divine creature should ever suffer from cold feet; a still greater pity that the coldness so often reaches to his heart. I look over the report of the doings of a scientific association and am surprised that there is so little life to be reported; I am put off with a parcel of dry technical terms. Anything living is easily and naturally expressed in popular language. I cannot help suspecting that the life of these learned professors has been almost as inhuman and wooden as a rain-gauge or self-registering magnetic machine. They communicate no fact which rises to the temperature of blood-heat. It doesn’t all amount to one rhyme.