This book was written as I taught an engineering course in circuits at the International University of Sarajevo. I tried to focus not only on opamps but add into the mix several relevant concepts. Since many non-electrical engineers took the course, it was important to frame the subject as a general engineering challenge, and to appeal to intuition. The hope is for the insights to carry over to other subjects of study as this heterogeneous group of readers would part their ways soon. I also wanted my students to see the human side of a practicing engineer. All with its shortcuts, rules of thumb, “back-of-the-envelope”s, and “good enough”s. The book follows step by step my class preparations. So it also embeds, to some extend, the contributions of the sophomore class of 2021. Parts where I had to revisit in subsequent class discussions naturally ended up covering more pages. The parts of the book skimmed over are the ones that class more readily understood and felt no further need for amplification. Most of it was written in real time, you might say, from late March to May, 2021.