so tilik's main work the most important work really is his three-volume systematic theology this is published say between 1951 and 1963 with the second volume published in 57. it's say three volumes but divided into five parts and it has the particular characteristic that each of the parts is structured according to uh a a a correlation so there are there are two pairs in each part um and i'll say a little bit more about specifics of correlation in in a second but the just to provide the context here these five parts um are in turn reason and revelation being and god existence and the christ life and spirit and history and the kingdom of god so i think already here we can have a sense of how it is that tillich's working how he's structuring this systematics this is not this is far from a dogmatics in perhaps the barten sense of a as it were systematic presentation of the doc of the contents of the christian faith this is right from the beginning a uh a deliberately structured presentation of the contents of christian theology in dialogue with what we might best understand as concerns or central features of human existence this is this is the idea of correlation yeah and this tillich famously defines as the method of correlation in terms of question and answer he he frames this in terms of there being existential questions that are raised which take particular forms in particular periods but you know these are the questions of uh what is it um to be where where have i come from where am i going why is there nothing why is there something rather than nothing why is there not nothing yeah what's the point of history is there a direction to history what is life these these existential questions sort of questions that concern some of us in moments when we have the time to reflect upon them and concerned philosophers on a professional basis philosophers and children anyway um the these are the existential questions yeah and until it responds to these with theological answers so he says revelation is the theological answer to the existential question of reason god is the theological answer to the eccentric question of being christ to existence spirit to life history kingdom of god to to to history yeah now this is very easily misunderstood um it can be misunderstood in two ways firstly we can misunderstand it as some kind of conservative response yeah so that culture philosophy human existence is okay with questions but answers come in from the religious traditions so there's there's a kind of um closing off almost of the human quest for you know uh um questioning uh and these are these theological answers come in and sort of you know shut that shut that off the other misinterpretation is that the answers are in some sense dependent upon or derived from worked up out of the questions of course that's the misinterpretation that is most common really that tilik is portrayed as being basically an existentialist philosopher who's kind of giving a religiously tinged interpretation of human existence but that really all the work is being done by the questions now i think both of those misinterpretations are in some sense encouraged perhaps by the form of question and answer and i think that that's the form that tillett used and it's there in print and we can't un-print that but i don't think it's necessarily the most helpful way of making the point that he wants to make in fact remember back to when we were talking about his earlier theology of culture there he talks about form content and substance religion is the substance of culture that's possibly a better model really that actually culture is both philosophy is both questioning and answering religion theology is both answering and questioning you know the point is that the two must be brought together so fertility any philosophy worth its salt becomes theology the heideggerian philosopher seeking the meaning of the question of being ceases to be a pure philosopher and becomes a theologian in starting to ask questions about the meaning of being and propose answers to those questions likewise any theologian must always be also doing philosophy the theologian who just simply produces chapter and verse sort of answers without being clear about the question that it is these answers are the answers to uh is is is no genuine theologian for telling so the correlation is more the interdependence the belonging together the indwelling of the existential and the religious and this has this enormously important consequence that fertility religion is relevant it's always relevant and yet it's always to be re-formulated in terms in response to in terms of in response to the situation that it's engaging with so that's the basis i think the the kind of core uh methodological point of of the systematics to go through the the the kind of um individual parts i mean we don't need to go through that in uh in such detail but um one of the key notions that tilik develops in the second part in terms of the correlation of god and being is the idea that god is to be thought of as being itself this is in a way the kind of correlative formulation of god it's of course uh a version of tillak's understanding of god is ultimate concern of the unconditioned that god is not a thing amongst other things god is that reality that sustains being he talks about the ground of being and that's sometimes quite mischievously presented as a sort of very abstract notion you know the pavement of