According to the text "Speaking and Doing by Mr. Wen Yiduo", talk about the meaning of the following sentences and pay attention to the meaning in bold. (1) At that time, he was already very poetic.

(1) "Poetry is exciting but not written" means that the interest in writing poetry decreases. In the 1920s, Wen Yiduo wrote many patriotic poems.

(2) "it" refers to the midnight light. Wen Yiduo made great efforts in academic research under the illumination of a solitary lamp. The mention of "bleaching the four walls" in this paper is intended to show Mr. Wen's comfortable situation of engaging in academic research late at night, which is in line with his interest of "opening up a bright road"

(3) The meaning of "concentration" and "concentration" is similar, which means that he is extremely focused and in-depth, and he is distracted from anything other than academic research.