( CNN ) -- They feature characters such as hat-wearing cats , very hungry caterpillars , nice girls named Madeline and naughty boys named Max . `` The Very Hungry Caterpillar '' by Eric Carle turns 40 this year , and 29 million copies of it have sold since 1969 . Parents read them to their children , forming a powerful bond . Years later , those former children read these children 's picture books to their children , and the thread between generations is extended yet again . `` Children 's books live a long time because you always have children growing into them , '' says Pat Scales , president of the Association for Library Service to Children and a retired school librarian . `` And parents read [ to their children ] what was read to them . '' The making of a classic is a strange alchemy of skill -- a good story , strong illustrations -- and luck . It 's not easy to appeal to three audiences : publishers , parents and -- oh , yes -- children . Dr. Seuss ' first children 's book , `` And to Think That I Saw It on Mulberry Street , '' was rejected by more than 25 publishers before Vanguard Press put it out in 1937 . Maurice Sendak 's legendary `` Where the Wild Things Are '' ( 1963 ) , though recognized with the Caldecott Medal -- the highest honor for a picture book -- was controversial for its drawings of monsters and its mischievous hero , Max . But almost all classics share some characteristics , says Alida Allison , a San Diego State University English professor and member of that California school 's National Center for the Study of Children 's Literature . `` Every one of them ... has the same reassuring pattern of 'home , away , home , ' `` she says . `` The basic plot begins with a happy family situation . Then one extremely curious or transgressive child goes out on his or her own . And , no matter how 'bad ' the child has been , he gets to come back home . '' The child is welcomed back to the family and often gets something to eat , she adds . ( One exception : Seuss ' `` Mulberry , '' in which the adult condemns the child 's sense of wonder -- but then , she adds , `` Dr. Seuss is in a world of his own . '' ) The plot is n't just reassuring to children , she points out , but also reinforces the lessons of good parenting . `` If you think of all those stories , there 's a loving parent ... allowing a transgressive kid a leash to investigate the world and come back , '' she says . And through the child 's eyes , parents find their sense of wonder renewed , she adds . For children , it 's all new -- the colors , the wordplay , even the plot -- and the more variety , the better . A child may be attracted by the rudimentary drawings of Eric Carle 's `` The Very Hungry Caterpillar , '' the elasticity of Seuss ' cats , Grinches and Oobleck , or the rich , almost otherworldly paintings of Chris Van Allsburg 's `` The Polar Express . '' And the language : Margaret Wise Brown 's `` Goodnight Moon '' may seem to be nothing much , but it 's as peaceful as a lullaby , Scales observes . And nothing succeeds like a book that has found its way into a child 's heart . `` We know that kids return to their favorite books over and over again , '' Scales says . And then , of course , the story starts from the beginning . Allison , a published author herself , read a variety of books to her children when they were growing up : Dorothy Kunhardt 's `` Pat the Bunny , '' Russell Hoban 's `` Frances '' books . But at least one title earned its way into the rotation because of an older fan : Allison 's husband . `` One of my husband 's favorites growing up was 'The Pokey Little Puppy , ' `` she says of the 1942 Little Golden Book by Janette Sebring Lowrey and Gustaf Tenggren . `` So he read that to our sons . ''
Parents often read to their children what was read to them when they were young . Children 's books help reinforce good parenting . Professor says ` ` home , away , away '' ' among books . ` ` ' Seuss is in a world of his own , '' professor says of story books .