“Venomous animals, when they bite or sting, inflict a wound, and instil into it a drop or more of liquor, which infects the fluid of the nerves, and by this means inflames the membranes: hereupon a swelling arises, sometimes to a degree of mortification, which spreads to the neighbouring parts.”

Book IV, lines 1133–1134 (reported in Bartlett's Familiar Quotations)
Variant translation: From the midst of the fountain of delights rises something bitter that chokes them all amongst the flowers.
Compare: "Still from the fount of joy's delicious springs / Some bitter o'er the flowers its bubbling venom flings", Lord Byron, Childe Harold's Pilgrimage, Canto I, stanza 82
De Rerum Natura (On the Nature of Things)

Source: Narcissus in Chains

Book I
The Advancement of Learning (1605)

As quoted in Liberalism is a Mental Disorder : Savage Solutions‎ (2005) by Michael Savage, Ch. 1 : More Patton, Less Patent Leather, p. 4

The Conspiracy of Kings (1792)
Context: Once draw the sword; its burning point shall bring
To thy quick nerves a never-ending sting;
The blood they shed thy weight of wo shall swell,
And their grim ghosts for ever with thee dwell. Learn hence, ye tyrants, ere ye learn too late,
Of all your craft th' inevitable fate.
The hour is come, the world's unclosing eyes
Discern with rapture where its wisdom lies;
From western heav'ns th' inverted Orient springs,
The morn of man, the dreadful night of kings.
Dim, like the day-struck owl, ye grope in light,
No arm for combat, no resource in sight;
If on your guards your lingering hopes repose,
Your guards are men, and men you've made your foes;
If to your rocky ramparts ye repair,
De Launay's fate can tell your fortune there.
No turn, no shift, no courtly arts avail,
Each mask is broken, all illusions fail;
Driv'n to your last retreat of shame and fear,
One counsel waits you, one relief is near :
By worth internal, rise to self-wrought fame,
Your equal rank, your human kindred claim;
'Tis Reason's choice, 'tis Wisdom's final plan,
To drop the monarch and assume the man.

Hippocrates - The Physician 14, as translated by Paul Potter, Loeb Classical Library, Hippocrates Volume VIII.
Context: Related to this is the surgery of wounds arising in military service, which concerns the extraction of missiles. In city practice experience of these is but little, for very rarely even in a whole lifetime are there civil or military combats. In fact such things occur most frequently and continuously in armies abroad. Thus, the person intending to practice this kind of surgery must serve in the army, and accompany it on expeditions abroad; for in this way he would become experienced in this practice.

Act III, scene 3.
The Honest Man's Fortune, (1613; published 1647)

Source: The Body

“Christ,” p. 106
The Sun Watches the Sun (1999), Sequence: “Is It Possible to Write a Poem”