A Ship Sailing Into Eternity

SM Stirling's The Golden Princess (New York, 2015), Chapter Twenty, presents an excellent account of the ambush and slaughter of a gang of would-be rapists. One paragraph ends with the death of a running man:

"He flopped forward onto his face, twitched and lay still, with the arrow standing from his spine like the mast of a ship sailing into eternity." (p. 503)

Not bad. Stirling's Nantucket Trilogy titles are:

Island In The Sea Of Time;
Against The Tide Of Years;
On The Oceans Of Eternity.

In The Golden Princess, the equation of eternity with navigable water occurs not as a title but as a metaphor in a single sentence. ("...like the mast of a ship..." is a simile but "...sailing into eternity..." is a metaphor.)

How does a dead man sail into eternity? We are always alive in the present. From our standpoint in the (eternal?) present, events recede into the past on the Einstein express at the speed of light. A man who is dead is completely in the past and therefore shares the unchangeability (eternity?) of all past events.

The man had been running forwards whereas the arrow/sail now stands up at right angles to the direction of his flight. This is appropriate. A flatlander, informed that three-dimensional space transcends his planar existence but unable to visualize the third dimension, might imagine that space is an infinite plane. Religious believers, told that eternity transcends time but unable to conceptualize anything transtemporal, imagine that eternity is endlessly prolonged time. Whatever eternity is, we are already in it - and also in time.

I think that the Christian cross can symbolize the relationship between time and eternity. The short horizontal line is time. The longer vertical line is eternity intersecting time in the present like the arrow in the man's back.