Fig.: a wishful thinking. A promise of either something pleasant - which is very unlikely to happen - or of a reward in heaven

Winning the lottery? It's all pie in the sky!

Vincere alla lotteria? Pia illusione!

To start and finish all this long and difficult work in a single day is just pie in the sky. Trust me!

Iniziare e completare tutto questo lavoro lungo e difficile in un solo giorno è una pia illusione. Credimi!

Our dream to live on a Caribbean island is still just pie in the sky. One day, when the kids are grown and all our debts are paid, this dream of ours can come true

Il nostro sogno di andare a vivere in un'isola dei caraibi è ancora solo una chimera. Forse, un giorno, quando i ragazzi saranno cresciuti e non avremo più debiti, il nostro sogno si avvererà

Zero-emission vehicles are not pie-in-the-sky ideas any more: they are already on the market place

Veicoli a emissioni zero non sono più solo belle promesse, ma sono già presenti sul mercato

This phrase was coined in 1906 by Joe Hill, a union organizer and songwriter, who wrote a song called The preacher and the slave, which parodied the Salvation Army hymn In the sweet bye and bye by Ira Sankey.
                    Work and pray,
                    Live on the hay,
                    You'll get pie in the sky when you die.
                    (That's a lie.)
The phrase wasn't taken up until the Second World War, when it began to be used figuratively to refer to promised pleasures that probably will never come true, or rewards that are given after you die