# First impressions redux

Once upon a time,
a child wrote a rhyme.
you can date this day,
if we know the moon,
and its springtime tune.

As for the aspect:

The answer is hidden in the lines of the poem.
It can be found by looking at the first word of each line, counting the number of letters in it,
and then taking the $n^{th}$ letter of the $n^{th}$ word of each line:

Once upon a time, $\hspace{8.5ex}$ E    Once = 4 letters; 4th letter of 4th word ("time") = E
a child wrote a rhyme. $\hspace{4ex}$ A    a = 1 letter; 1st letter of 1st word ("a") = A
It asked for the way, $\hspace{5ex}$ S    It = 2 letters; 2nd letter of 2nd word ("asked") = S
you can date this day, $\hspace{4ex}$ T    you = 3 letters; 3rd letter of 3rd word ("date") = T
if we know the moon, $\hspace{5.7ex}$ E    if = 2 letters; 2nd letter of 2nd word ("we") = E
and its springtime tune. $\hspace{2ex}$ R    and = 3 letters; 3rd letter of 3rd word ("springtime") = R

And so we have our answer confirmed at last.

• Ah, well done! I could clearly see those letters of Easter sitting in that rhyme, but the scheme eluded me. I kept trying to make sense out of 4-1-4-9-4-9. The check mark belongs here. – Amit Naidu Apr 4 '18 at 4:03
• This post uses steg, to crack out the egg. So let me embark, with no more remark, to strike the checkmark! – Tom Apr 4 '18 at 15:05

Easter, because it is Easter weekend and its date in the Gregorian calendar is based on the spring equinox and the ecclesiastical full moon.

I couldn't find the referenced child, but here is the rhyme by English poet Justin Richardson (1900-1975):

No need for confusion if we but recall That Easter on the first Sunday after the full moon following the vernal equinox doth fall.

There is a similar Scottish poem too, but it does not employ the vernal equinox as its reference.

• Impressive first post, but to count on the checkmark, the steganography tag needs applied to show the hidden word. – Tom Apr 1 '18 at 7:42