There are two main reasons for performing or listening to compilations. Either (1) you want to join the best bits and able to listen to together or (2) in order to both a historical and discover different facets of one kind or group. The assessment of "best bits" is always difficult and subject to the tastes and stories of each. The meeting of the best pieces is never as successful as when made yourself. So listening to a compilation applies particularly to the discovery (or rediscovery) of certain securities / lesser known groups or one does not possess. This compilation is no exception to the rule. We can always discuss an "essential" as missing or choosing a piece over another, especially when the goal is to represent an entire musical genre here with such progressive rock. Personally, I rejoiced rather the lack of Pink Floyd songs, Genesis or King Crimson. These groups are so essential to the genre that I know not recommend listening to all Pink Floyd (until Final cut), all Genesis and Yes' 70s and the first King Crimson. Their absence thus leaves a little room for other pieces of interest. What could be more open to criticism in this case is that many of the titles are quite short and that one of the essential beauty of the progressive rock lies in an atmosphere that requires quite a long time listening. An entire album and / or allow long titles to appreciate better the atmosphere and the high points (and low) works. However well we understand that this was not feasible on just two disks (or even 6 with complement wondrous strories in 4 volumes). So we have here a selection which includes big names in progressive or some notable titles like. The whole is rather disparate but overall enjoyable and very interesting. Included are tracks from psychedelic roots (the kettle, a whiter pale, paper sun), some more rock titles (and thankfully not too heavy, not too many) (Radar love, Jail Bait) of folk influences (Rhayader , Dust in a wind, Northern lights) or more complex-and closer to the essence of progressif- (Crime, Frankenstein, wind, Catherine, the 4 horsemen). The spotlight is (naturally) dedicated to 67-75 years (almost 75% of the shares) while the rest covers the following 8 years. This album finally book many samples that reveal genre and can make people want to deepen. That is the essential and much fun compilations.