Zoonomia; Or, the Laws of Organic Life, Vol. I - Erasmus Darwin

Now in strong lines, with bolder tints design'd,

You sketch ideas, and portray the mind;

Teach how fine atoms of impinging light

To ceaseless change the visual sense excite;

While the bright lens collects the rays, that swerve,

And bends their focus on the moving nerve.

How thoughts to thoughts are link'd with viewless chains,

Tribes leading tribes, and trains pursuing trains;