Two Types of Genius and Intelligence

Raymond Cattell observed two distinct types of intelligence: fluid intelligence (innovative capacity, working memory, problem-solving speed) which rises through the 20s and 30s and peaks in the late 30s/early 40s before declining, and crystallized intelligence (accumulated knowledge, wisdom, pattern recognition, vocabulary, teaching ability) which increases through the 40s, 50s, and 60s and stays high into the 70s and 80s.