Ema and Goliath didn't receive a letter, the letter was in the same place from the beginning, and they came to the letter, saying about what was about to happen and also promising the truth if they went to Zimirt.
On Olympus, letters with instructions to each one of them also appeared, except for Yuriel and Isaac's clones.
"For Edward only." Edward took it; each one contained a secret that shall not be revealed to anyone in case of them being captured by Nature.
All of them were using similar objects as Edward's compass that prevents Nature from finding them, and Olympus was also beyond her reach, but that means nothing when they are out in the wilds with many other living beings.
Every letter contained different instructions but started with the same speech from the Constructor.
