Care and Mental Health, published in 1951. Bowlby drew together such limited empirical evidence as existed at the time from across Europe and the US. His main conclusions, that "the infant and young child should experience a warm, intimate, and continuous relationship with his mother (or permanent mother substitute) in which both find satisfaction and enjoyment" and that not to do so may have significant and irreversible mental health consequences, were both controversial and influential. The 1951 WHO publication was highly influential in causing widespread changes in the practices and prevalence of institutional care for infants and children, and in changing practices relating to the visiting of infants and small children in hospitals by parents. The theoretical basis was controversial in many ways. He broke with psychoanalytic theories which saw infants' internal life as being determined by fantasy rather than real life events. Some critics profoundly disagreed with the necessity for maternal (or equivalent) love to function normally, or that the formation of an ongoing relationship with a child was an important part of parenting. Others questioned the extent to which his hypothesis was supported by the evidence. There was criticism of the confusion of the effects of privation (no primary attachment figure) and deprivation (loss of the primary attachment figure) and in particular, a failure to distinguish between the effects of the lack of a primary attachment figure and the other forms of deprivation and understimulation that may affect children in institutions. The monograph was also used for political purposes to claim any separation from the mother was deleterious to discourage women from working and leaving their children in daycare by governments concerned about maximising employment for returned and returning servicemen. In 1962 WHO published Deprivation of maternal care: A Reassessment of its Effects to which Mary Ainsworth, Bowlby's close colleague, contributed with his approval, to present the recent research and developments and to address misapprehensions. This publication also attempted to address the previous lack of evidence on the effects of paternal deprivation. According to Rutter, the importance of Bowlby's initial writings on "maternal deprivation" lay in his emphasis that children's experiences of interpersonal relationships were crucial to their psychological development. Development of attachment theory In his 1988 work A Secure Base, Bowlby explained that the data was not, at the time of the publication of Maternal Care and Mental Health, "accommodated by any theory then current and in