I'm sorry. I should have invested more time to reply. Anyway, I understood it completely - after years of experience SOLID comes natural to you. That's exactly the thing - it was natural and logical to me even before I had any touch with the theory. I have to thank my high school teachers for that, because they used a different kind of teaching techniques which placed deductive thinking above any concrete knowledge. The result of that type of teaching is a different perspective when learning strictly defined technical stuff - like programming. To me, SOLID principles are unnecessary theoretical bloatware, and poorly defined in many sources (offline books or online learning resources). Many of those sources are complicating things too much when explaining SOLID principles, but the principles are easy and generally applied on auto-pilot - just like you explained in the publication. To me, any theory which needlessly overcomplicates simple concepts and is trying to make a whole science out of it is bad and counterproductive.