[Lalaith]

Here you go, this quote should give you some help:
OF THE LAWS AND CUSTOMS AMONG THE ELDAR
PERTAINING TO MARRIAGE AND OTHER MATTERS
RELATED THERETO: TOGETHER WITH THE
STATUTE OF FINWE AND MIRIEL AND THE DEBATE
OF THE VALAR AT ITS MAKING.

AElfwine's Preamble.

The Eldar grew in bodily form slower than Men, but in mind
more swiftly. They learned to speak before they were one year
old; and in the same time they learned to walk and to dance, for
their wills came soon to the mastery of their bodies. Nonetheless
there was less difference between the two Kindreds, Elves and
Men, in early youth; and a man who watched elf-children at play might well have believed that they were the children of
Men, of some fair and happy people. For in their early days
elf-children delighted still in the world about them, and the fire
of their spirit had not consumed them, and the burden of
memory was still light upon them.
This same watcher might indeed have wondered at the small
limbs and stature of these children, judging their age by their
skill in words and grace in motion. For at the end of the third
year mortal children began to outstrip the Elves, hastening on to
a full stature while the Elves lingered in the first spring of
childhood. Children of Men might reach their full height while
Eldar of the same age were still in body like to mortals of no
more than seven years. Not until the fiftieth year did the Eldar
attain the stature and shape in which their lives would after-
wards endure, and for some a hundred years would pass before
they were full-grown.