Why are the shops shut today?

I was shopping at Auchan yesterday morning. There was a large sign outside that said that the shop would be shut on Sunday 19 May. At the check-out, I asked the cashier to confirm this, and the following dialogue ensued:

Me: Sklep jest jutro zamknięty? ['The shop is shut tomorrow?']
Cashier: Zamknięty. Jakieś święto. ['It is shut. Some religious feast.']

Jakieś święto. 'Some religious feast.' One wouldn't say that about Christmas or Easter, or about secular holidays, such as Independence Day or Constitution Day. I'm sure everyone - from the youngest to the oldest, of all levels of eduction - would be able to say or even write something meaningful about each of those days.

But today's feast - Pentecost - is as mysterious as the Holy Spirit himself (yes, He's male). Ask all but the most knowledgeable Catholics what Pentecost is about, and you'll not get too many illuminating answers. On All Saints' Day, Poles will visit their ancestors' graves - a moving tradition that most Poles participate in. Christmas and Easter are exceptionally important holidays and religious feasts. But closing the shops to commemorate the Holy Spirit's descending upon the Twelve Apostles seems a bit... obscurantist. Have you ever bought or sent any Pentecost cards to friends or family? So why should this day rank alongside Christmas and Easter as a day when shops should be shut?

Pentecost Sunday was made a day off work in 2006 by that bizarre coalition of PiS, LPR and Samoobrona. It affects mostly retailers, though petrol stations remain open. It keeps catching many Poles off-guard, as Pentecost is not one of those religious feasts that people automatically look forward to or have in their family calendars.

So why have it? It reflects a rare blend of traditional, religious conservatism and left-wing  trade-unionism that's extremely Polish. I cannot see the Parliamentary Labour Party agitating for shops to be shut in the UK on Pentecost Sunday. Well, as I can't go shopping today, I'll go for a walk or something!

This time last year:
Jeziorki at its most beautiful

This time three years ago:
Useful and useless in my wallet

This time four years ago:
In search of the dream klimat - remote viewing made real

This time five years ago:
Zakopane to Kraków in 3hrs 45min

This time six years ago:
The year's most beautiful day?