The last English edition of widely acclaimed and highly popular "Quantum Mechanics" of D.I.Blokhintsev was arranged based on 3rd and 4th Russian editions and published by Reidel in 1964. Since then, D.I. Blokhintsev prepared the revised and updated 5th edition (1976), with main changes affecting the concluding Ch. 25 "The Conclusions". As the revised edition was not available so far to an English-speaking audience and to bridge this gap, we undertook an English translation of that concluding chapter. 25. In the process, §137, The formalism of quantum mechanics, which underwent no changes in a new edition, was reproduced from the 4th 1964 Reidel edition, and §141, dedicated mostly to elementary particles, was omitted as an outdated one.There is a little doubt that the original text, created almost half a century ago, would look differently if written in our days and age. However, we introduced no edits, except for just a few editorial notes, to preserve Author’s unique style and render a spirit of the legendary times.Needless to say, D.I.Blokhintsev was among founding fathers (along with L.E.Ballentine and K.V.Nikolsky) and a passionate proponent and advocate of the Statistical Interpretation of Quantum Mechanics. His concept of Quantum Ensembles, tracing back to earlier works of von Mises and von Neumann, proved instrumental for a modern understanding of Quantum Mechanics and demystifying the paradox of Quantum Non-locality / "spooky action" at the distance. Considering a nowadays progress in Quantum Computing and related need in a clarification of foundations of Quantum Mechanics, we hope this translation will be welcomed by a physics community working at all stripes of Quantum Mechanics.