The Church has always taught that the threefold ministries that mark the life and work of the diaconate form a single whole whose parts can never be compromised or lost. The bishops teach this truth very clearly:
Therefore, diaconal ministries distinguished above are not to be separated; the deacon is ordained for them all, and no one should be ordained who is not prepared to undertake each in some way. A deacon may also have greater abilities in one aspect of ministry; therefore, his service may be marked by one of them more than by the others. Fundamentally, however, there is an intrinsic unity in a deacon’s ministry (NDPD, art. 39).
Thus, every aspirant who wishes to discern a vocation to the diaconate must be ready to serve the fullness of diaconal ministry when and if he is ordained a deacon.