He sat down without saying a word to anybody, and began to reflect.
This event might have three causes: The first and the most natural was that it might be an ambuscade of the Rochellais, who might not be sorry to kill one of his Majesty's Guards, because it would be an enemy the less, and this enemy might have a well-furnished purse in his pocket.
D'Artagnan took his hat, examined the hole made by the ball, and shook his head.

The ball was not a musket ball--it was an arquebus ball.

The accuracy of the aim had first given him the idea that a special weapon had been employed.

This could not, then, be a military ambuscade, as the ball was not of the regular caliber.
This might be a kind remembrance of Monsieur the Cardinal.

It may be observed that at the very moment when, thanks to the ray of the sun, he perceived the gun barrel, he was thinking with astonishment on the forbearance of his Eminence with respect to him.
But d'Artagnan again shook his head.