Back to the alphabet.

Et:

What I like about one of the usual ways of reciting and singing the alphabet is it takes off with a bang, like a shot into the air, but it slows down dramatically at the end, like a slowly falling leaf, to mix metaphors. I wouldn't say the alphabet exactly as you wrote it above. In order to show the slow down, I'd show it slightly differently:

a_b_c_d_e_f_g___
h_i_j_k_
lmnop___
q_r_s___
t_u_v___
w._x_
y___
z___

Or:
abcdefg_
hijk[lmno]p
qrs
tuv
w
x
y
z

(and the [lmno]in brackets to show compressed time)

So, even though not symmetrical, it's finally satisfying dramatically--quick pace at the upper end settles down at the end.

Heart beat: auditory training.

Well, yeah. But there's also the beat of the feet that is implanted deeply in our psyches when we walk--and the quickened tempo that's implanted, too, when we run. And the distinctive galloping and skipping rhythms (both distinct from each other, by the way--have you ever noticed?)...and so on. Being bipeds, we have all kinds of rhythms deeply embedded inside us from childhood on. Even crawling must have embedded something musical inside us. Bach used to compose inside his head by walking many miles to organ recitals. He'd set his lines to match his pace. We are natural metronomes and we can change our tempo at will.

If you're interested in how strongly connected are the body and music, take a look into the Delcroze method. Jacqueline Du Pré's mother, a highly accomplished pianist, was also an instructor in the method which provides many bridges between dance, movement, kinesthetics and music. And Du Pré's mother provided Delcroze training for both Jackie and her sister when they were young.

So, it's the heart, yes. But it's more than the heart. It's our feet and our arms and our fingers and even our toes. It may be the blink of our eyes, too. The heart is that persistent ostinato, its tempo influenced by our physical and emotional reactions. But we carry other constant music makers around with everything we do--if we have ears to hear.