Non-static method Waavi\Translation\Repositories\Repository::find() should not be called statically, assuming $this from incompatible context

This code in my controller

$language = LanguageRepository::find(1);

throws out the following error:

Non-static method Waavi\Translation\Repositories\Repository::find() should not be called statically, assuming $this from incompatible context

Can somebody tell me why does it is giving me this error?

via Chebli Mohamed