Amongst the big questions about humanity from "Who am I?" to "Where am I", there is the subject of consciousness relayed by philosophy and theology at first and then by biology, psychology, sociology and more recently by cognitive sciences. This book attempts to reconcile these disciplines through the common denominator of consciousness, but on one of its specific aspect. The book presents a concept of-motivation of field of activity, as a biological motor of a state of consciousness, and of which system informatics enables to reveal its existence. If consciousness is not well defined, a limited frame provides a more precise and observable definition despite the context complexity of the individuals: psychological, social and technical. These observable elements are of two nature: a nature of principal activity and a cognitive-linguistic nature, which are adapted with extrinsic and intrinsic control factors. The argument presented here consists in presenting a state of consciousness as related to the concept of instinctive (therefore physiological) information need, and whose carrier traces on the traditional information channels, i.e. letters and subscriptions and on the modern information channels, i.e. text messages and web pages, can be analyzed via knowledge extraction.