A Picture of Prayer
"If a son shall ask bread of any of you that is a father, will he give him a stone? or if he ask a fish, will he for a fish give him a serpent? Or if he shall ask an egg, will he offer him a scorpion? If ye then, being evil, know how to give good gifts unto your children: how much more shall your heavenly Father give the Holy Spirit to them that ask Him?" Luke 11:11-13

From the human perspective, read about an importunate petitioner and an unwilling provider in Three Friends. Here from the divine perspective, we have earthly evil providers contrast with the willing heavenly Provider.

Bread (staple), fish (supplement), egg (savoury) sustain and strengthen natural life.
Stone (hard), serpent (harmful), scorpion (hurtful) devastate and destroy life

The Holy Spirit sustains and strengthens spiritual life by His good gifts and graces.

"He that spared not His own Son, but delivered Him up for us all, how shall He not with Him also freely give us all things?" Romans 8:32