Due to different factors, including those related to the particular political relationship between the United States and the Soviet Union, Vygotsky's work remained unknown in the Americas for decades. When the Cold War ended, the incredible wealth of Vygotsky's work began to be revealed. Nowadays, it is difficult to exclude Vygotsky from any serious discussion of learning processes. The origins of thought and language according to Vygotsky Like in animals, thought and speech have different roots in humankind, thought being nonverbal and language being nonintellectual in an early stage. But their development lines are not parallel - they cross again and again. At a certain moment around the age of two, the curves of development of thought and speech, until then separate, meet and join to initiate a new form of behavior. That is when thought becomes verbal and speech becomes rational. A child first seems to use language for superficial social interaction, but at some point this language goes underground to become the structure of the child's thinking.Word meaning and concept formation... a problem must arise that cannot be solved otherwise than through the formation of new concepts. (Vygotsky, 1962:55)

Once the child realizes that everything has a name, each new object presents the child with a problem situation, and he solves the problem by naming the object. When he lacks the word for the new object, he demands it from adults. The early word-meanings thus acquired will be the embryos of concept formation.Vygotsky's social constructivismAccording to Vygotsky, all fundamental cognitive activities take shape in a matrix of social history and form the products of sociohistorical development (Luria, I 976). That is, cognitive skills and patterns of thinking are not primarily determined by innate factors, but are the products of the activities practiced in the social institutions of the culture in which the individual grows up. Consequently, the history of the society in which a child is reared and the child's personal history are crucial determinants of the way in which that individual will think. In this process of cognitive development, language is a crucial tool for determining how the child will learn how to think because advanced modes of thought are transmitted to the child by means of words (Murray Thomas, 1993).Thought and language, and intellectual developmentTo Vygotsky, a clear understanding of the interrelations between thought and language is necessary for the understanding of intellectual development. Language is not merely an expression of the knowledge the child has acquired. There is a fundamental correspondence between thought and speech in terms of one providing resource to the other; language becoming essential in forming thought and determining personality features.Zone of proximal development One essential tenet in Vygotsky's theory is the notion of the existence of what he called the "zone of proximal development".