To get to the bottom of someone's mind/ to grasp his meaning

To understand someone's intention; to grasp the depth of what they are saying.

("It is known before the One who spoke and the world came into being that in the generation of Rabbi Meir there was no one like him, and why did they not establish the halakhah according to him? Because his colleagues could not get to the bottom of his mind. For he would declare impure what was pure and show him reasons, declare pure what was impure and show him reasons" - Eruvin 13b; and similarly: "And I also studied the whole subject of idolatry, and it seems to me that no work in the world on this subject has remained ... until I read it, understood its contents, and got to the bottom of his mind" - Maimonides / Epistle to the Sages of Montpellier on the Decree of the Stars, 438; and similarly: "He hinted to us with his hand toward the door. We got to the bottom of his mind, for he is hinting to us to leave" - Shalom Aleichem / HaHavurah, 179; and similarly: "With a long delay and a lag, when you never once got to the bottom of her love, I remind you / how we used to be embraced" - Natan Yonatan / Zikaron leGavriel Freil; and similarly: "A great writer lived in Jerusalem... many people were waiting for a new work of his, and scholars delved to get to the bottom of his mind and debated it in discussion" - Chaim Savatov / Ke'af'apei Shachar, 19)

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