17. The apparatus of claim 16 , wherein the search expression is a first search expression; the other content items are first other content items; the user also uses a second content item, and the search expression generator is to further: receive a constituent of the second content item, wherein the second content item is also a selected one of a web page, a post to a social networking site, a post to a blog, a post to an online bulletin board, a document, an electronic message, a product description, an entertainment description, or an advertisement, having text divisible into a plurality of subtexts; and generate a second search expression based on the constituent of the second content item, to search second other content items, through execution of the second search expression, wherein the second search expression includes a hierarchy of a plurality of nested juxtaposition sub-expressions corresponding with nesting of subtexts of the constituent of the second content item; wherein the second search expression is to be applied by the search engine operated on the same or a different apparatus, to the second other content items to generate a second search result.
16. An apparatus for consuming a content item, comprising: one or more hardware processors and memory; and a search expression generator to be operated by the one or more processors to: receive the content item, wherein the content item is a selected one of a web page, a post to a social networking site, a post to a blog, a post to an online bulletin board, a document, or an electronic message, having text divisible into a plurality of subtexts; and generate a search expression based on the content item, to search other content items, through execution of the search expression, wherein the search expression includes a hierarchy of a plurality of nested juxtaposition sub-expressions corresponding with nesting of subtexts of the content item; wherein the search expression is to be applied by a search engine operated on the same or a different apparatus, to the other content items to generate a search result; wherein generate comprises recursively dividing the text of the content item into the subtexts, and transform the subtexts into the search sub-expressions; and wherein the content item is a first content item, and the search result includes a second content item to be recommended to a user.