Bethsheba Comment:
Fort appears to be related by etymology to the word four; four walls to a house gives strength to the structure. Fort is from the Latin fortis meaning: strong, mighty; firm.
Island * 4 = 620.
Take this value to the next verse too.

Fortify it!

The Old Comment
Fortify it! = Concentrate the mind upon it.

The New Comment
{WEH NOTE: There is no New Comment to this verse.}