可遇不可求

can be discovered but not sought (idiom) / one can only come across such things serendipitously

can / may / able to / to approve / to permit / to suit / (particle used for emphasis) certainly / very

used in 可汗[ke4 han2]

surname Yu

to meet / to encounter / to treat / to receive / opportunity / chance

no; not so / (bound form) not; un-

cannot / should not / must not

cannot; should not; must not

to seek / to look for / to request / to demand / to beseech