I pray thee, mark me.
I, thus neglecting worldly ends, all dedicated
To closeness and the bettering of my mind
With that which, but by being so retired,
O’erprized all popular rate, in my false brother
Awaked an evil nature, and my trust,
Like a good parent, did beget of him
A falsehood in its contrary as great
As my trust was, which had indeed no limit,
A confidence sans bound.

– William Shakespeare

The Tempest, Act 1, Scene 2. Prospero doesn’t think his young teen daughter Miranda is paying enough attention to his tale of betrayal by brother Antonio, as he keeps saying "mark me." He tells her that while he neglected practical matters as Duke of Milan and bettered his mind with studies, this awakened an evil nature in Antonio. His trust in his brother was so strong that he didn’t see his treachery coming.