It (Tao) is eternally without desire. So, it can be called small. All things return to it, although it does not make itself their ruler. So, it can be called great.
When good thing are accomplished, it does not claim (or name) them. This is Te, which is close in meaning to power or virtue. It is something within a person, and it is enhanced by following the Tao, or 'that from which nothing can deviate'.