Both sides want transparency to be the default.
Mr Davis, taking up the historical theme, quoted British wartime leader Winston Churchill.
"The pessimist see difficulty in every opportunity, the optimist sees opportunity in every difficulty".
He added: "Bridging between Churchill and Monet, I am certainly a determined optimist".
The chief stewards of the United Kingdom economy, speaking in their delayed annual Mansion House addresses in London on Tuesday, said breaking up financial services such as derivatives and lending after Britain leaves the European Union would result in higher costs for companies.
Johnson said that while there would be "lots of discussions about the nature of the deal, about money and so on, the most important thing is to raise our eyes to the future".
Talks will begin at 0900 GMT with a joint press conference by former French foreign minister and European commissioner Barnier and Davis at around 1630 GMT.
Kane rescues draw for England against Scotland in qualifying
A sparky opening had filtered out throughout the first 45 minutes apart from Kane's chances. There was a real quality finish as well, under pressure, to get the point", he said.
The Chancellor insisted the economy must be a priority as Britain negotiates with Brussels, saying the public "did not vote to become poorer" when they backed Brexit in last year's referendum.
Those issues are Britain's exit bill, estimated by Brussels at around 100 billion euros (USD 112 billion), the rights of three million European Union nationals living in Britain and one million Britons on the continent, and the status of the border between Northern Ireland and Ireland. A day after the start of Brexit talks, Hammond sought to soften the more confrontational tone towards the bloc taken by Prime Minister Theresa May - a role he has re-adopted since her election flop earlier this month.
In choreographed talks that saw the two men exchange mountaineering gifts, they agreed to discuss divorce issues before negotiations on a future trade deal can start.
The chancellor - strengthened since the general election - gave the greatest detail yet about what his approach might mean for our future relationship with the EU.
In the recent election the two main parties shared 82% of the vote, with both affirming the intention to leave, and to leave the single market and customs union as well. It now numbers 28 members.
Acknowledging the hard talks ahead, British Secretary for Brexit David Davis, said the talks would be held in a constructive and positive atmosphere, and would deliver a deal "that works in the best interests of all citizens".
Leaving the European Union, he added, could not be to the detriment of investment, enterprise or increased productivity - which he said held the key to the UK's future economic growth and the government's ability to pay for increased funding for public services at a time of growing "weariness" over austerity.
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