Was Crocodile stronger at Marineford? Or was he holding back in Alabasta?

 During the Alabasta arc, Crocodile displayed a level of power that was initially considered overwhelming by the Straw Hat Pirates. He possessed the Logia-type Devil Fruit called the Suna Suna no Mi (Sand-Sand Fruit), which granted him the ability to control and transform into sand. He had a reputation as a Shichibukai and controlled the desert kingdom of Alabasta from the shadows. His strength was showcased through his battles with Luffy and others. At Marineford, Crocodile was present as part of the war that took place at Marine Headquarters. While he did participate in the battle, he didn't display the same level of dominance as some other powerful characters present. This has led fans to speculate that he might not have been as strong as initially portrayed in Alabasta. It's important to note that power scaling and character abilities can be subject to interpretation and development by the author. Oda often keeps details deliberately open-ended to keep the story intriguing.

What did Friedrich Engels mean when he said that "communism is not for us a state of affairs which is to be established, an ideal to which reality will have to adjust itself"?

 Friedrich Engels was a German philosopher and political theorist who, along with Karl Marx, is considered one of the founders of communism. In his statement, Engels was expressing the idea that communism is not an ideal or utopia that can be achieved in the future, but rather a natural outgrowth of historical development.

According to Engels and Marx, communism is the final stage of social evolution, in which the class distinctions and conflicts that have characterized human society throughout history will be abolished and all people will be able to live in harmony and equality. The idea is that as society progresses, the means of production (such as factories and farms) will become increasingly owned and controlled by the workers themselves, rather than by a small group of capitalists. This, in turn, will lead to the abolition of private property and the creation of a classless society.

Therefore, Engels was saying that communism is not something that can be created by simply implementing a certain set of policies or by trying to achieve a certain ideal. Instead, it is the result of the natural evolution of society as it moves towards greater equality and cooperation.