The earliest reference I could find was to a poem by Thomas Hardy from 1909, “The Dead Man Walking”:
THEY hail me as one living,
But don’t they know
That I have died of late years,
Untombed although?
I am but a shape that stands here,
A pulseless mould,
A pale past picture, screening
Ashes gone cold.
Not at a minute’s warning,
Not in a loud hour,
For me ceased Time’s enchantments
In hall and bower.
There was no tragic transit,
No catch of breath,
When silent seasons inched me
On to this death….
—A Troubadour-youth I rambled
With Life for lyre,
The beats of being raging
In me like fire.
But when I practised eyeing
The goal of men,
It iced me, and I perished
A little then.
When passed my friend, my kinsfolk,
Through the Last Door,
And left me standing bleakly,
I died yet more;
And when my Love’s heart kindled
In hate of me,
Wherefore I knew not, died I
One more degree.
And if when I died fully
I cannot say,
And changed into the corpse-thing
I am to-day,
Yet is it that, though whiling
The time somehow
In walking, talking, smiling,
I live not now.
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I tried to look for the phrase in the OED online, but didn’t find anything.