Akash Pratap Singh

I've been reading a book on electronics and in it, in the section where it discusses transformers, it uses a line to explain why there are no dc transformers, and I don't quite get it (I understand the reason why there can't be dc transformers but not the one the book is trying to point to). Can someone help me understand? The line goes as quoted
" Magnetizing inductance causes a primary current even with no secondary load; more significantly, it means that you cannot make a “dc transformer.”