“...play [is] an instinct developed by natural selection ... and ... on a level with the other instincts which are developed for… — Karl Groos Instinct Copy Share Image
“...play, so far from being "by play," if I may so speak, is a matter of serious moment to the creature. Play… — Karl Groos Instinct Copy Share Image
“...imitation supplements inadequate congenital variations in the direction of an instinct, and so, by keeping the creature alive, sets the trend of… — Karl Groos Heredity Copy Share Image
“Imitation is a real instinct, but it is not always playful; play is a real instinct, but it is not always imitative.… — Karl Groos Imitation Copy Share Image
“But as we ascend to animals of high types, having faculties more efficient and more numerous, we begin to find that time… — Karl Groos Needs Copy Share Image
