Makes me forgetful?

Brutus: Yes, Cassius, and from henceforth,
When you are over-earnest with your Brutus,
He'll think your mother chides, and leave you so.

And all this on the brink of disaster and death.

But here comes a rare touch, and we might as well quote it in full.

Mind you, I am following Shakespeare, and not history, which is mostly
lies.

A great poet's instinct might be nearer the truth; after all. Of
course scholars know that Macbeth (or Macbethad) reigned for upwards
of twenty years in Scotland a wise and a generous king--so much so
that he was called "Macbathad the Liberal," and it was Duncan who
found his way to the throne by way of murder; but it didn't fit in
with Shakespeare's plans, and--anyway that's only a little matter
between the ghosts of Bill and Mac which was doubtless fixed up long
ago. More likely they thought it such a one-millionth part of a
trifle that they never dreamed of thinking of mentioning it.

(Noise within.)

Poet (within): Let me go in to see the generals; There is some
grudge between 'em--'tis not meet
They be alone.

Lucilius (within): You shall not come to them.