“Theory is grey my friend but the tree of life blooms forever green”, as Lenin put it quoting Goethe. It means that society, class struggle and politics do not develop in simple linear ways but in surprising and unforeseeable forms requiring new tactics and analysis.
History does not move at a uniform pace and in direct ways: it jumps, stops and doubles back on itself. At times it feels less like a tree and more like a bramble patch. Not only that but new movements and social developments do not express themselves directly but often in old forms and languages.