Possible Clues:

• "My mistress' eyes are nothing like the sun" quintet
• Shakespeare's 'Shall I compare thee to a summer's day?' has five of them
• There are 70 in a Shakespearean sonnet
• Pope's feet?
• "Shall I compare thee to a summer's day?" quintet
• 'Shall I compare thee to a summer's day?' quintet
• Feet with rhythm?
• Feet in a sonnet
• Trio in "To be, or not to be"
• Some two-syllable feet