I do not know the reasons to give me the name JACEK - my mother does not remember. Thanks to that I have five letters in my name and five in my surname - altogether it gives 10 letters. Furthermore my birthday is on December 10th and my nameday is on February 10th. I must say that number 10 is my favourite. But what is the origin of the name JACEK? After researches and thanks to help from Mr. Wojciech Jóźwiak I have learned out that the origin is not Slavic but Greek or even from the language of some older nation. Jacek comes from the name Hiacynt (Hiacynth) which comes from the Greek *Hyakinthos*.

Myth of Hyakinthos

Hyakinthos, the young son of the King of Sparta, beautiful like the very gods of Mount Olympos, was the friend of Apollo, shooter of arrows. Apollo often came down to the shores of the Eurotas River in Sparta to spend time with his young friend. They would go hunting together through the woods and glades on the mountain sides, or they would practice gymnastics, a skill for which the Spartans were renowned.
Once, in the heat of a summer afternoon, Apollo and Hyakinthos were throwing the heavy discus, and each was trying to outdo the other. The bronze discus flew higher and higher, almost reaching the sky. Finally, the powerful god gathered all his strength, and spun and wheeled and let fly the shiny discus which rose swift as a bird until it reached the clouds. Then, glittering like a star, it began to tumble down.
Hyakinthos ran towards the place the discus was headed. He was hurrying to take his turn, to prove to Apollo that he, though just a young athlete, was no less able than the god at throwing the discus. The discus landed, but having fallen from such a great height it bounced back up and violently struck Hyakinthos in the head. [another version says that Zephir also was in love with Hyakinthos and he made the discus hit the lad to punish Apollo and his friend] He let out a groan and crumpled to the ground. The blood spurted thickly from his wound, coloring crimson the curly black hair of the handsome youth.
Horrified, Apollo raced over. He bent over his friend, raised him up, rested the boy's head on his knees, trying desperately to staunch the blood flowing from the wound. But it was all in vain. Hyakinthos grew paler and paler. His eyes, always so clear, lost their gleam and his head rolled to one side, just like a flower of the field wilting under the pitiless rays of the noonday sun. Heartbroken, Apollo cried out: "Death has taken you in his claws, beloved friend! Woe, for by my own hand you have died. Why did I have to cast the discus so high? Oh, if only I could pay for my deed by joining you in your journey to the cheerless realms of the dead. Oh, why am I cursed to live forever? Why can't I follow you?
Apollo held his dying friend close to his breast, and his tears fell in a stream onto the boy's bloody hair. Hyakinthos died, and his soul flew to the kingdom of Hades. The god bent close to the dead boy's ear, and softly whispered: "In my heart you will live forever, beautiful Hyakinthos. May your memory live always among men as well." And lo, at a word from Apollo, a fragrant red flower rose from Hyakinthos's blood. We call it hyacinth, and on its petals you can still read the sigh of pain that rose from Apollo's breast.
It is possible that the name JACEK would not survive in Poland (especially with that homosexual conotation). Thanks to Saint Jacek Odrowąż (student of Saint Dominic) my name was listed with other names of the saints and therefore become available to give to children.

It is worth to notice that the ending -inthos in the Greek names suggests a name of the place, like in the names Corinth or Probalinthos. But where is Hyak?

The Spanish and Portugese equivalent of JACEK is Jacinto.