“But it may be said that the plant is void of reason, because the growth of a plant is an involuntary growth.  Given earth, air, and due temperature, the plant must grow:  it is like a clock, which being once wound up will go till it is stopped or run down:  it is like the wind blowing on the sails of a ship—­the ship must go when the wind blows it.  But can a healthy boy help growing if he have good meat and drink and clothing? can anything help going as long as it is wound up, or go on after it is run down?  Is there not a winding up process everywhere?

“Even a potato {5} in a dark cellar has a certain low cunning about him which serves him in excellent stead.  He knows perfectly well what he wants and how to get it.  He sees the light coming from the cellar window and sends his shoots crawling straight thereto:  they will crawl along the floor and up the wall and out at the cellar window; if there be a little earth anywhere on the journey he will find it and use it for his own ends.  What deliberation he may exercise in the matter of his roots when he is planted in the earth is a thing unknown to us, but we can imagine him saying, ’I will have a tuber here and a tuber there, and I will suck whatsoever advantage I can from all my surroundings.  This neighbour I will overshadow, and that I will undermine; and what I can do shall be the limit of what I will do.  He that is stronger and better placed than I shall overcome me, and him that is weaker I will overcome.’

“The potato says these things by doing them, which is the best of languages.  What is consciousness if this is not consciousness?  We find it difficult to sympathise with the emotions of a potato; so we do with those of an oyster.  Neither of these things makes a noise on being boiled or opened, and noise appeals to us more strongly than anything else, because we make so much about our own sufferings.  Since, then, they do not annoy us by any expression of pain we call them emotionless; and so qua mankind they are; but mankind is not everybody.

“If it be urged that the action of the potato is chemical and mechanical only, and that it is due to the chemical and mechanical effects of light and heat, the answer would seem to lie in an inquiry whether every sensation is not chemical and mechanical in its operation? whether those things which we deem most purely spiritual are anything but disturbances of equilibrium in an infinite series of levers, beginning with those that are too small for microscopic detection, and going up to the human arm and the appliances which it makes use of? whether there be not a molecular action of thought, whence a dynamical theory of the passions shall be deducible?  Whether strictly speaking we should not ask what kind of levers a man is made of rather than what is his temperament?  How are they balanced?  How much of such and such will it take to weigh them down so as to make him do so and so?”