Surrealist theatre and Artaud's "Theatre of Cruelty" were inspirational to many within the group of playwrights that the critic Martin Esslin called the "Theatre of the Absurd" (in his 1963 book of the same name). Though not an organized movement, Esslin grouped these playwrights together based on some similarities of theme and technique; Esslin argues that these similarities may be traced to an influence from the Surrealists. Eugène Ionesco in particular was fond of Surrealism, claiming at one point that Breton was one of the most important thinkers in history.[70][71] Samuel Beckett was also fond of Surrealists, even translating much of the poetry into English.[72][73] Other notable playwrights whom Esslin groups under the term, for example Arthur Adamov and Fernando Arrabal, were at some point members of the Surrealist group.