Nowadays our mothers act like friendship is an elective—falling somewhere down the list after husbands, children, career, home, money.
-- Carmen (Prologue)

Importance: Carmen talks about how all of the girls knew one another since before they were born as their mothers were all in an exercise class for pregnant women. She laments that their mothers didn't value their friendship more, and believes that they don't see the value of friendship.

Tonight we give the Pants the love of our Sisterhood so we can take that love wherever we go.
-- Bridget (chapter 1)

Importance: Bridget says this as the friends are consecrating the Pants as the symbol of their love for each other.

She’d decided the morning after the vow of the Pants that she was going to record her summer of discontent in a movie - a suckumentary, a pastiche of lameness.
-- Tibby (chapter 1)

Importance: This is how Tibby views the world and is also what motivates her...