Page:The Art of Preserving Health - A Poem in Four Books.djvu/113

25Nor less the labours of the mind corrode
The solid fabric.For by subtle parts,
And viewless atoms, secret Nature moves
The mighty wheels of this stupendous world.
By subtle fluids pour'd thro' subtle tubes
30The natural, vital, functions are perform'd.
By these the stubborn aliments are tam'd;
The toiling heart distributes life and strength;
These the still-crumbling frame rebuild; and these
Are lost in thinking, and dissolve in air.

35But 'tis not Thought (for still the soul's employ 'd)
'Tis painful thinking that corrodes our clay.
All day the vacant eye without fatigue
Strays o'er the heaven and earth; but long intent
On microscopic arts its vigour fails.
40Just so the mind, with various thought amus'd,
Nor aches itself, nor gives the body pain.