Once, we believed our lives were sacred, that we had souls. Now we know we are mere machines; genetic data. We are science.
But even as we learn, the properties of life remain uncertain. How does life acquire consciousness, or rights? Does a robot dream? If a person transforms into an oak tree, is it science or the work of gods? Did the Victorians find a way to resurrect the dead?
To science, such questions are invitations to explore. Who better to explore with than the Doctor?
life n. : 1: The state of being which begins with generation, birth, or germination, and ends with death; also, the time during which this state continues. 2: Of human beings: the union of the soul and body; also, the duration of their union; sometimes, the deathless quality or existence of the soul.
From the very beginnings of DNA itself, the essence of life has been renewal and change. As genetic data mutates, replicates, replaces its forerunners and adapts to its environment, the diversity of life is ever-changing, ever-growing. And as we discover more about the processes that make us what we are, so we also gain the power to change them — and even to create life in new and unfamiliar ways.
With the Doctor, this new world of scientific frontiers opens up into a whole universe of possibilities — some horrific, some mysterious, some beautiful. A robot discovering its capacity to dream. A living language, expanding to control and subjugate the human population. A life form that connects one universe and another, lurking in the London Underground. Virtual-reality people, living a not-so-virtual life of their own. An auctioneer of body parts, developing his own new life forms from the remains of others. A sentient android, whose form and thoughts have grown from a telepathic link with the occupants of the TARDIS.
The Doctor himself, of course, is not immune to change, and the passage of time takes its toll on his body and his soul. But even as he sees his friends and enemies age and die beside him, his own life is somewhat different — and every now and again, he becomes an entirely new man...