A little confuse here. What is the middle section of the page? Is he alluding the middle of every line? If not, then I interpret it as "eyes go down in a straight line down the centre" as others, but he said that interpretion was wrong in his comment above. So what does he mean in the last sentence?
An important question at this juncture is: do you need to move the guide along the entire line ( he presented the visual guide techniques at that point)
The answer to this quetion may be found in the common knowledge that speed readers read down the middle of the page. This is often misinterpreted as meaning that their eyes go in a straight line down the centre. This is not the case. What they do is to read down the middle section of the page
I assume he means that when you "read down the middle of the page" your eyes are neverthless still flicking from side to side, rather than moving in a straight line down the page. However, the area thus scanned does not extend right to the edges of the page, but is confined to the central section.
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