The Ways of the Tzaddikim is a classic book on Jewish ethics, covering topics under the rubric of different gates (joy, worry, cruelty, love). Each gate outlines the positive and negative elements of both positive and negative human traits. For even love, taken to extremes, can cause harm, and hate, when properly harnessed, can lead to good. This is in keeping with the very practical attitude of traditional Judaism to human motivation and drives.
I’m not sure of this work’s compositional history. It does not appear to have an author, but rather be a compendium of different works, largely not cited (with the exception of a large chunk of Maimonides’ Introduction to the Mishnah Torah). This can make for choppy and repetitive reading.
But for someone interested in old school Torah, this won’t matter. Pick up the book and put it down. Inhale the fragrance of true belief married to certainty of action and intent. That is what this book is for: to provide the path for excellent behavior; and that path is bound to be a bit twisted.