## Mathematicians Of The Day

### 29th January

On this day in 1670, James Gregory wrote to John Collins:
Mr Barrow, in his Optics, showed himself a most subtle geometer, so that I think him superior to any that ever I looked upon: I long exceedingly to see his geometrical lectures, especially because I have some notions upon that same subject by me. I entreat you to send them to me presently as they come from the press, for I esteem the author more than you can easily imagine.

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#### Quotation of the day

##### From Eduard Kummer
It is greatly to be lamented that this virtue of the real integers that they can be decomposed into prime factors which are always the same for a given integer does not belong to the complex integers [of arbitrary cyclotomic number fields], for were this the case, the entire theory, which is still labouring under many difficulties, could easily be resolved and brought to a conclusion.
De numeris complexis, qui radicibus unitatis et numeris integris realibus constant 1847