According to the Wikipedia a 'firth' is a Scots word used to denote various coastal waters in Scotland. It is usually a large sea bay, which may be part of an estuary, or just an inlet, or even a strait. One of the firths mentioned there is the Firth of Forth.
Without ever having been there, I reckon that this songs describes a (perphaps fictitious) similar landscape. There may also be religious thoughts embodied in the text, but I haven't worked that angle out yet.
According to the Wikipedia a 'firth' is a Scots word used to denote various coastal waters in Scotland. It is usually a large sea bay, which may be part of an estuary, or just an inlet, or even a strait. One of the firths mentioned there is the Firth of Forth.
Without ever having been there, I reckon that this songs describes a (perphaps fictitious) similar landscape. There may also be religious thoughts embodied in the text, but I haven't worked that angle out yet.