The wind eased itself gently through Captain Sheba's hair as he pressed his eye against his spy glass. "Land! At last we are rich!" he shouted to his crew members. They anchored not very far away from the strange little island, rowed toward the shore and arrived safely. "Brethren, we've found the island. From the information we have so far, the treasure is hidden under one of these colored rocks on the shore and the rest of the rocks have a poisonous gas trapped beneath them. Alas, I can't afford to lose any of my crew members. If we could only decode the last part of these writings, we would know which rock the treasure is under. I will give ten percent of the find to anyone who is able to decode this last message!"

At the end of your power
At the beginning of eternity
Blessed is he who finds me
He who still exists after uncovering me
To enjoy my riches forever
My last is in mud somewhere wherever

That's all the writings say. There are four rocks. They are blue, red, white, and black respectively. Which one has the treasure hidden under it?