The aim of the article is to demonstrate that cognitive linguistic methodologies can provide a basis for analyses of literary and poetical works. I attempt to fully interpret A Poison Tree written by William Blake. The analysis is based on the beliefs of the Theory of Conceptual Metaphor. I also refer to cognitive conception of emotions (Lakoff, Kӧvecses, Johnson). Rosh’s model of categorization has also been mentioned. I assumed, among others, after Langacker that linguistic meanings are individual in character and dependent on the author’s experiences.