A Word She Knows

At bedtime your names, spoken, act on her
Like a two-toned bell on Pavlov's dog.
She waves a small hand,
Secure in the fact
She knows best,
And her lips twist
To form a soft 'bye,' which she repeats
A score of times, while my heart
Beats an involuntary echo, before
She sinks into the nest I built
Of blankets for her rest.