I copy Brenda's translation ,hope it could be helpful
from http://www.italki.com/answers/question/71469.htm
The ancient character "羊" has featured the frontal of the sheep head. The sheep was one of the important domestic animals in the ancient animal husbandry. The ancestors offered the sheep as sacrifice to the gods to pray for the peace and happiness. The sheep was placed beside "示" which meant the tablet belonging to the gods. "示", as a componet showing the meaning, suggests auspicious and lucky. "祥" consists of the two components of "示" and "羊" which suggests the pronounceation of the character, this kind of phonomenon is called echoism in Chinese. Therefore, "祥" is a associative and pictophmetic character.
