The beginning of the sentence, 'não assim [...]', doesn't make so much sense out of context, since apparently it refers to something said just before, through the implicit imperfect past conjugation of the verb 'ser'. I looked on Google for that sentence and have found the complete paragraph, within the article's context (I've added some words between brackets for you to understand it better): 'Ovalle poeta foi bem diverso de Ovalle músico. Eram duas almas distintas na mesma pessoa. A música de Ovalle foi a sublimação do sentimento e das formas populares absorvidas por ele na sua infância e na sua verde mocidade. Não [era] assim [o caso da] sua poesia, cujas raízes estavam na Bíblia, salvo a [raiz] da [sua] lírica amorosa, de natureza extremamente sofisticada.' ~ 'The poet Ovalle was very diverse from the musician Ovalle. They seemed to be two different souls inside the same person. Ovalle's music was the apotheosis of the sentiment and the popular art expressions that he absorbed in his childhood and early youth. However, that was not the case regarding his poetry, whose roots were based on the Bible, except for his lyrical, love poetry, whose roots were very sophisticated in nature.' Hope it helps!

The beginning 'Não assim' is clarified by a sentence before, which Tatyana has already provided in a comment. A possible translation is: "So was not his poetry, which has roots rather in the Bible, except for the lyric love works, given their extremely sophisticated character".

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