Sentence:  One <WSD>is</WSD> not sure who emerges as the main personality of this book - Mijbil , with his rollicking ways , or Maxwell himself , poet , portrait painter , writer , journalist , traveller and zoologist , sensitive but never sentimental recorder of an unusual way of life , in a language at once lyrical and forceful , vivid and unabashed . 
Meaning of the word marked with <WSD> tags:  have the quality of being; (copula, used with an adjective or a predicate noun)