There is an envelope marked with the instructions that it is not to be opened until the death or disappearance of Dr. Jekyll. This implies that Dr. Lanyon knew something secret, but was unwilling to reveal it at first. He waited until there was no more "hope" of Dr. Jekyll staying normal.
<span>The best information from the story helps you check the
prediction that Dr. Lanyon will reveal shocking information about Dr. Jekyll is
the passage, "Within there was another enclosure, likewise sealed, and marked
upon the cover as 'not to be opened till the death or disappearance of Dr.
Henry Jekyll.”</span>
