Sentence:  She looked at the girl speculatively from eyes which had paled with the years ; from the early evening lights of them which had first startled Izaak to look at her in an uncousinly way , they had faded to a near absence of color which had , <WSD>possibly</WSD> from her constant looking at the water , something of the light of the sea in them . 
Meaning of the word marked with <WSD> tags:  by chance