Operators letting blood from the arm of a woman in a room crowded with pharmacy jars. Oil painting by Egbert van Heemskerck.

The operators are wearing the distinctive hats of mountebanks and other open-air performers. However the painting shows them operating in an etablished surgeon-apothecary's premises. The contrast might be explained by a passage in Sir Thomas Overbury's "Characters": A quacksalver ... All the diseases ever sinne brought upon man, doth he pretend to bee curer of; when the truth is, his maine cunning, is corne-cutting. ... He parts stakes with some apothecary, in the suburbes at whose house hee lies: and though he be never so familiar with his wife; the apothecary dares not (for the richest horne in 's shoppe) displease him. All the midwives in the towne are his intelligencers; but nurses and yong merchants wives that (would faine conceive with childe) these are his idolaters. Hee is a more unjust bone-setter, then a dice-maker; he hath put out more eyes then the smal pox; made more deafe then the cataracts of Nilus; lamed more than the gout: shrunke more sinewes, then one that makes bow strings, and kild more idly, then tobacco. A magistrate that had any way so noble a spirit as but to love a good horse wel, would not suffer him to be a farrier. His discourse is vomit, and his ignorance, the strongest purgation in the world: to one that would be speedily cured, he hath more delaies and doubles then a hare, or a law suit: hee seekes to set us at variance with nature, and rather then wee shall want diseases, hee'le beget them. His especiall practise (as I said afore) is upon women; labors to make their mindes sicke, ere their bodies feele it, and then there's work for the dog-leach. Lastly he is such a juggler with urinals, so dangerously unskilfull, that if ever the city will have recourse to him for diseases that neede purgation, let them imploy him in scouring Moore-ditch." ("Sir Thomas Overbury his wife. With additions of new characters", London 1615)