It is both coming to terms with and fighting these moments that who we are as people are laid out before us as we live every day, with the internal skirmishes shaping who we will become and allowing us at times to leave who we were before in the past, for better or for worse.
The Doctor's Daughter is full of different variants of this theme from a war that has spanned "generations" to examples of how unwilling soldiers such as the Doctor himself deal with the wars within and the ones in the outside world.
It also features the Doctor's actual daughter, a clone made from the Doctor's DNA that struggles mildly between the Doctor's peaceful ways and the soldier culture she was created to fight for.
Meanwhile, most of the cloned residents of the colony planet are also waging a battle between never ending war and the peace they believe will come with gaining the source, a mystical object that divides the planet between Human and Haith.
Moral directions and themes can either lift up or virtually scar a plot or story, but in this case it works as it should, buried in the goings on in a way that is both subtle and strong enough to get it's point across without losing any of it's bite and realism along the way.
As far as plots go, this is Doctor Who's Doctor Who, and you could quite easily replace the Doctor and Donna Noble with any Doctor/companion combination, but this is more of a strong point then a let down, a testament to the strength of Stephen Greenhorn's script and to the fact that even in the midst of Doctor Who's fourth series since it's return to television, certain things remain the same.
This is evident as we are thrown straight into a hostile alien planet's affairs, split from at least one of the Tardis crew and lots and lots of running down corridors getting chased by the enemy.
Donna Noble keeps showing that she was indeed the right choice for a full time companion, she uses what talents she has to her advantage, surprising even the Doctor in the process.
At the end of the day I think this story will gain more respect as time passes and be considered one of the better episodes of the fourth series, if not the new run all together.
It is a mix of classic Doctor Who themes and the modern era's emotional nature, proving that both can co-exist with the right script and the right kind of pacing.
Now, speaking of pacing, if you'll excuse me, I have lots of running to do.