Fernando Pessoa wrote his poetry under several different names -heteronyms -conceived of as independent authorial personalities equivalent to the author himself. The first heteronym, Alberto Caeiro, and an important part of his work are said to have appeared at the same time under the influence of a sort of epiphanic inspiration. Pessoa 's account of this creative session is very detailed, and critics have accepted it without any difficulty. During it Pessoa-Caeiro is said to have written in its definitive version and without any preparation about thirty poems of The Tender of The Flock cycle. An examination of the material elements, however, tells a different story : all the poems have rough drafts, fair copies and several revisions ; their order in the cycle was changed several times and it is not certain that it reached its final state. There is thus a contradiction between the author's statements and the genetic documents relating to his text. The writing- materials, types of documents, rewritings -everything points to a slow creation by trial and error, forming a rich whole from the double point of view of the evolution and significance of the poems and the total conception of Caeiro 's work. One can even wonder whether many of these poems were not first written «by Pessoa », later changing then-language, rhetoric and signature. In the manuscripts of The Tender of the Flock, we find numerous cases where the meaning of the text is affected by elements of a strictly material nature. Furthermore, the denying of the author's words is a consequence of the existence of manuscripts carefully conserved by him. There is an archive created by the author with the aim of correcting the meaning of words that can no longer be taken as a biographical document, but rather as a fiction to surround the poetry written under another name. The author's grouping together of the manuscripts has a semiotic value which takes a bird's eye view of the manuscripts themselves and of the verbal «territory » covered by the text. Could one speak of semiotics of an archive ?