One night he lost all moral control, and tying the hind legs of two cats together with a piece of string, he flung the animals into Van Baerle’s garden.  To Boxtel’s bitter mortification the cats, though they made havoc of many precious plants before they broke the string, left the four finest tulips untouched.

Shortly afterwards the Haarlem Tulip Society offered a prize of 100,000 guilders to whomsoever should produce a large black tulip, without spot or blemish.  Van Baerle at once thought out the idea of the black tulip.  He had already achieved a dark brown one, while Boxtel, who had only managed to produce a light brown one, gave up the quest as impossible, and could do nothing but spy on his neighbour’s activities.

One evening in January 1672, Cornelius de Witt came to see his grandson, Cornelius van Baerle, and went with him alone into the sacred drying-room, the laboratory of the tulip-grower.  Boxtel, with his telescope, recognised the well-known features of the statesman, and presently he saw him hand his godson a packet, which the latter put carefully away in a cabinet.  This packet contained the correspondence of John de Witt and M. de Louvois.

Cornelius drove away, and Boxtel wondered what the packet contained.  It could hardly be bulbs; it must be secret papers.

It was not till August, as we know, that Craeke was despatched to Van Baerle with the note bidding him destroy the packet.

Craeke arrived just when Van Baerle was nursing his precious bulbs—­the bulbs of the black tulip—­and his sudden entrance rudely disturbed the tulip-grower.  He had not time to read the note; indeed, he was too much concerned with the welfare of his three particular bulbs to trouble about it, before a magistrate and some soldiers entered to arrest him.  Van Baerle wrapped up the bulbs in the note from his godfather, and was sent off under close custody to The Hague.  The magistrate carried off the packet from the cabinet.

All this was Boxtel’s work.  It was he who had reported to the magistrate the visit of De Witt and the placing of the packet in a cabinet.  And now, with Van Baerle out of the house as a prisoner, Boxtel in the dead of night broke into his neighbour’s house, to secure the priceless bulbs of the black tulip.  He had made out where they were growing, and he plunged his hands into the soft soil—­only to find nothing.  Then the wretched man guessed that the bulbs had gone with the prisoner to The Hague, and decided to go in pursuit.  Van Baerle could only keep them while he was alive, and then—­they should be his, Isaac Boxtel’s.

III.—­The Theft of the Tulip

Van Baerle was placed in the cell occupied by Cornelius de Witt in the Buytenhof.  Outside, in the market-place, the bodies of the De Witts were hanging, and Van Baerle read with horror the inscription, “Here hang that great rascal John de Witt and the little rascal Cornelius de Witt, enemies of their country.”