shakespeare quotes: There are more things in heaven and earth

Hamlet:


Swear by my sword

Never to speak of this that you have heard.

Ghost:


[Beneath] Swear by his sword.

Hamlet:


Well said, old mole, canst work i' th' earth so fast?

A worthy pioner! Once more remove, good friends.

Horatio:


O day and night, but this is wondrous strange!

Hamlet:


And therefore as a stranger give it welcome.

There are more things in heaven and earth, Horatio,

Than are dreamt of in your philosophy.

Hamlet Act 1, scene 5, 159–167

Horatio and Marcellus, though advised against it, barge into Hamlet's conversation with his father's ghost [see SOMETHING IS ROTTEN IN THE STATE OF DENMARK].
Hamlet is a little unforthcoming with the news imparted by this spirit,
who is still rustling about under the stage. So it's hard to figure
what Horatio and Marcellus are being asked to keep quiet, though Hamlet
and the burrowing ghost (a "pioner," or miner) insist.

Horatio, a model of rationality, is still having a hard time
swallowing the whole business. Ghosts are not the sort of beings his
"philosophy" easily takes into account. We know that Horatio is, like
Hamlet, a student at the University of Wittenberg, a notable outpost of
Protestant humanism. The philosophy he studies there is probably
classical—a compound of ethics, logic, and natural science. The
emphasis on everyday phenomena pretty much excludes speculation about
talking ghosts.

Wittenberg, however, isn't just a place where sober-minded Horatios
debate Aristotelian physics. In Christopher Marlowe's play of the late
1580s, Doctor Faustus, it is where the doctor lectures and, on the sideline, fraternizes with demons.