The incident just related was, as the reader has guessed before this, the diabolical work of Mynheer Isaac Boxtel.
It will be remembered that, with the help of his telescope, not even the least detail of the private meeting between Cornelius de Witt and Van Baerle had escaped him. He had, indeed, heard nothing, but he had seen everything, and had rightly concluded that the papers intrusted by the Warden to the Doctor must have been of great importance, as he saw Van Baerle so carefully secreting the parcel in the drawer where he used to keep his most precious bulbs.
The upshot of all this was that when Boxtel, who watched the course of political events much more attentively than his neighbour Cornelius was used to do, heard the news of the brothers De Witt being arrested on a charge of high treason against the States, he thought within his heart that very likely he needed only to say one word, and the godson would be arrested as well as the godfather.
Yet, full of happiness as was Boxtel's heart at the chance, he at first shrank with horror from the idea of informing against a man whom this information might lead to the scaffold.
But there is this terrible thing in evil thoughts, that evil minds soon grow familiar with them.
Besides this, Mynheer Isaac Boxtel encouraged himself with the following sophism:-"Cornelius de Witt is a bad citizen, as he is charged with high treason, and arrested.
"I, on the contrary, am a good citizen, as I am not charged with anything in the world, as I am as free as the air of heaven."
"If, therefore, Cornelius de Witt is a bad citizen,--of which there can be no doubt, as he is charged with high treason, and arrested,--his accomplice, Cornelius van Baerle, is no less a bad citizen than himself.
"And, as I am a good citizen, and as it is the duty of every good citizen to inform against the bad ones, it is my duty to inform against Cornelius van Baerle."
Specious as this mode of reasoning might sound, it would not perhaps have taken so complete a hold of Boxtel, nor would he perhaps have yielded to the mere desire of vengeance which was gnawing at his heart, had not the demon of envy been joined with that of cupidity.
Boxtel was quite aware of the progress which Van Baerle had made towards producing the grand black tulip.
Dr. Cornelius, notwithstanding all his modesty, had not been able to hide from his most intimate friends that he was all but certain to win, in the year of grace 1673, the prize of a hundred thousand guilders offered by the Horticultural Society of Haarlem.