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4 ^

56 A DISCOURSE

and if this be true and gonstant, all our imbibitions of salts and compostssignify little to Earth pre-impregnated with a salt or virtue different fromwhat the plant does naturally delight in, some obscure footsteps of whichevery ploughman seems to discover, which makes him change the cropin some places yearly. For the first, second, or third burden of the samegrain, especially wheat, will exhaust that which is its proper aliment,and then leave the rest to more ignoble grain, which will be found tothrive well enough, till at last several succefsions of different seeds quitewear it out, and then the land must repose, or be manured with compostsfor fresh life and vigour k . And to this we may add, how some plants againrequire little change or help of art; such as moil of the perennial greens,and amongst these the most resinous and oily, as the pine, fir, cedar, &c.which thrive on barren hills, and grow in rocky crannies, without anyEarth almost to cover and protect their roots. Of this sort I have a cedartable, which was sawed out of a spur only of a monstrous tree growingin Barbadoes , which held fix feet long, five feet broad, and three inchesthick, formed and wrought as it stands upon the frame ; and his Royal

Highnefs had another of a much larger dimension; namely, eighteenfeet in length, and nine in breadth, cut out of the stem, which wasof prodigious growth, fed and nourished as it was between the barren

Hoc e fonte fluit, me judice, fabula Graium;

Haec olim aripedes Tauri, vigilesque DraconesVellera servavere, hac ibat dote per undasMedea, his visus renovari fructibus ,'Eson,

Et succo przesente senex revocafse juventam.” Connub. Fjlor.

* It does not seem a well-founded opinion, that plants of different kinds select differentparticles from the same Earth . Accurate experiments rather prove that they all live uponthe same general food. Some require more, some lels. Some take it near the surface,others take it deeper. Upon these principles we may rationally account for the necefsity ofchanging the species in the old husbandry. With regard to the different tastes and odoursof different plants growing upon the same bed of Earth , I shall only remark, that the mo-dification of the particles of the general nutriment produces all the differences. Matter,considered as matter, has no share in the qualities of bodies. It is from the arrangement ofit that we have so many substances in nature. We may eat the earth, and drink the waterthat moistens it, and yet front the modification of its parts by the different vefsels of plants,it is capable of becoming both bread and poison. A lemon, grafted upon an orange stock* *is capable of changing the sap of the orange into its own nature, by a different arrange-ment of the nutritive juices. The same mafs of innocent Earth can give life and vigour tothe bitter aloe, and to the sweet cane ! to the cool houseleek, and to the fiery mustard! tothe nourishing grains, and to the deadly nightshade!