Two forms of intellectual activity: association and dissociation.—Abstraction belongs to the second type. Its positive and negative conditions. It is a case of attention: psychical reinforcement.—It is in embryo in concrete operations: in perception, and the image. Its practical character.—Generalisation belongs to the first type. Problem of the _primum cognitum_; difference or resemblance?—Hierarchy of general ideas: need of a notation. Three great classes.—Lower forms of abstraction and generalisation or pre-linguistic period, characterised by absence of words 1 ANIMALS. Different observations. Numeration in animals; what does it consist of?—Mode of formation and characteristics of generic images. Reasoning in animals.—Reasoning from particular to particular: how this differs from simple association.—Reasoning by analogy.—The logic of images: its two degrees; its characteristics. Does not admit of substitution; always has a practical aim.—Discussion of certain cases 11 CHILDREN. Does intelligence start from the general or the particular? A badly-stated question. Intelligence proceeds from the indefinite to the definite.—Characteristics of generic images in children; examples.—Numeration; its narrow limits. Difference between real numeration and perception of a plurality 31 DEAF-MUTES. These furnish the upper limit of the logic of images.—Their natural language. Vocabulary. All their signs are abstractions. Syntax of position; disposition of terms according to order of importance.—Intellectual level 39 ANALYTICAL GESTURES. General classification of signs.—Gesture, an intellectual, not an emotional, instrument; its wide distribution. Syntax identical with that of deaf-mutes.—Comparison between phonetic language and language of analytical gesture.—Reason why speech has prevailed 48 CHAPTER II. SPEECH.