et it be; the fathers shall see that I am a believer," cried
the prince.

Immediately one of the brothers put his own cloak, three-cornered hat,
and mask upon his highness, still remaining cloaked and masked himself,
much to the astonishment of the passive prince. "Come, now, the
Invisibles await you," said one of the masked. The prince stepped
courageously into the little corridor which led to the secret stairway,
one brother preceding him, causing a soft light to illumine their path,
the other following him.

In silence they reached the side-door of the palace, where a close
carriage awaited them.

"Where are you taking me?" asked Frederick William, as he entered,
followed by the two brothers.

"To the Invisibles," answered a strange voice.

Again the prince essayed to begin a conversation, his only response
being, "Purify your heart and pray." Silently they galloped over paved
and unpaved streets, the prince heartily repenting having been drawn
into this adventure. He thought of his charming and beloved Wilhelmine,
and half determined to give the command to drive to Charlottenburg. The
fact of Bischofswerder being with him, and fearful of appearing weak
and wanting in courage in the eyes of his friend and favorite, prevented
him.

After several hours' drive, they stopped at the marble palace of
Potsdam, near the one which the prince was accustomed to occupy. His
highness looked cautiously around, and breathed more freely, as he felt
that he was now surely among friends.

The white palace stood silent and deserted in the darkness, this palace
at Potsdam being only used for the guests of the king. The carriage
stopped at the side-door, where there was no sentinel, and they
alighted, entering the palace, winding along the corridors in the same
order as before, guided by the glimmering light of the one preceding.
Solemn music, strange ringing sounds, fell upon the ear as they
advanced. Sometimes they were sharp and cutting as glass, then
threatening and penetrating as the wind, shrieking and moaning, causing
one to be very nervous if not terrified.

The farther they proceeded the louder grew the sounds, and at intervals
groans, moans and wailings were heard, as of those waiting and imploring
for mercy.

One of the brothers now opened a door, and then placing themselves
upon each side, the unknown voice announced to the prince that they had
arrived at the long-sought-for goal.

"What have we come here for?"