海の物とも山の物ともつかない

Expression – implying lack of experience and an inability to grasp the essence of things

Source – Bengarachou Hakubutsushi

この小説家というのがまだ二十歳そこそこの、自作を世に問うたのがほんの一・二編の、海のものとも山のものともつかぬ駆け出しだとぶちまけてしまえば、途端に重厚な印象は失せて、飛び方を習い覚えたばかりの若鳥の、まだ柔らかそうで小生意気な嘴くちばしばかりが目についてくる。

Translation

This so-called writer was still around the age of 20, and of those works he brought to the fore, questioning the epoch he was situated in, were only one or two volumes – and thus he was a beginner that had neither grasped the seas nor the mountains, so to put it quite frankly, we can lose that profound vision of depth, and see him as a young fledgling chick learning how to fly, cheekily pecking about with his soft beak.